Bellringers Animals

Rabbits

2009-11-28T17:22:00.000-08:00

Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world. There are seven different genera in the family classified as rabbits, including the European rabbit (Oryctolagus cuniculus), Cottontail rabbit (genus Sylvilagus; 13 species), and the Amami rabbit (Pentalagus furnessi, endangered species on Amami Ōshima, Japan). There are many other species of rabbit, and these, along with pikas and hares, make up the order Lagomorpha.

The rabbit lives in many areas around the world. Rabbits live in groups, and the best known species, the European rabbit lives in underground burrows, or rabbit holes. A group of burrows is called a warren. Meadows, woods, forests, thickets, and grasslands are areas in which rabbits live. They also inhabit deserts and wetlands. More than half the world's rabbit population resides in North America. They also live in Europe, India, Sumatra, Japan, and parts of Africa. The European rabbit has been introduced to many places around the world. The rabbit's long ears, which can be more than 10 cm (4 in) long, are probably an adaptation for detecting predators. They have large, powerful hind legs. Each foot has five toes, with one greatly reduced in size. They are digitigrade animals; they move around on the tips of their toes. Wild rabbits do not differ much in their body proportions or stance, with full, egg-shaped bodies. Their size can range anywhere from 20 cm (8 in) in length and 0.4 kg in weight to 50 cm (20 in) and more than 2 kg. The fur is most commonly long and soft, with colors such as shades of brown, gray, and buff. The tail is a little plume of brownish fur (white on top for cottontails).
Rabbits are hindgut digesters. This means that most of their digestion takes place in their large intestine and cecum. In rabbits, the cecum is about 10 times bigger than the stomach, and it, along with the large intestine, makes up roughly 40% of the rabbit's digestive tract. Cecotropes, sometimes called "night feces", come from the
cecum and are high in minerals, vitamins and proteins that are necessary to the rabbit's health. Rabbits eat these to meet their nutritional requirements. This process allows rabbits to extract the necessary nutrients from their food.

Rabbits have two sets of incisor teeth, one behind the other. This way they can be distinguished from rodents, with which they are often mistaken.

Rabbits, being prey animals, tend to be exploratory in new spaces and when confronted with a threat, they tend to freeze and observe. Rabbit vision has a remarkably wide field of vision, and a good deal of it is devoted to overhead scanning. Even indoors, rabbits will scan for overhead threats.

Rabbits have a complex social structure, and like dogs, will attempt to establish a hierarchy and dominance.

Female rabbits do not actually ovulate until after breeding. They have a bifurcated uterus and often, breeding can involve multiple acts that can result in multiple impregnations from different bucks (male rabbits). Males are commonly sterile during the heat of summer months.
A litter of rabbit kits (baby rabbits) can be as small as a single kit, ranging up to 12 or 13; however there have been litters as big as 18. The gestation period is 30–32 days.

Rabbits are herbivores who feed by grazing on grass, forbs, and leafy weeds. In consequence, their diet contains large amounts of cellulose, which is hard to digest. Rabbits solve this problem by passing two distinct types of feces: hard droppings and soft black viscous pellets, the latter of which are immediately eaten. Rabbits reingest their own droppings (rather than chewing the cud as do cows and many other herbivores) to digest their food further and extract sufficient nutrients.

Pet rabbits kept indoors are referred to as house rabbits. House rabbits typically have an indoor pen or cage and a rabbit-safe place to run and exercise, such as an exercise pen, living room or family room. Rabbits can be trained to use a litter box and some can learn to come when called. Domestic rabbits that do not live indoors can also often serve as companions for their owners, typically living in an easily accessible hutch outside the home. Some pet rabbits live in outside hutches during the day for the benefit of fresh air and natural daylight and are brought inside at night.

Whether indoor or outdoor, pet rabbits' pens are often equipped with enrichment activities such as shelves, tunnels, balls, and other toys. Pet rabbits are often provided additional space in which to get exercise, simulating the open space a rabbit would traverse in the wild. Exercise pens or lawn pens are often used to provide a safe place for rabbits to run.

A pet rabbit's diet typically consists of unlimited Timothy hay, a small amount of pellets, and a small portion of fresh vegetables. Rabbits are social animals. Rabbits as pets can find their companionship with a variety of creatures, including humans, other rabbits, guinea pigs, and sometimes even cats and dogs. Animal welfare organisations such as the House Rabbit Society recommend that rabits do not make good pets for small children because children generally do not know how to stay quiet, calm, and gentle around rabbits. As prey animals, rabbits are alert, timid creatures that startle easily. They have fragile bones, especially in their backs, that require support on the belly and bottom when picked up. Children 7 years old and older usually have the maturity required to care for a rabbit.

Crocodile

2009-10-12T15:41:00.000-07:00

The largest captive crocodile alive in the US is located in South Carolina. In June 2002, Alligator Adventure introduced Utan. At 20 feet (6.1 m) long and weighing in at more than a ton, "Utan", the largest crocodile to ever be exhibited in the United States, made his new home in Myrtle Beach.

The largest recorded crocodile is a giant saltwater crocodile measured at 8.6 metres (28 ft) and 1,352 kilograms (2,980 lb) shot in Australia, Queensland in 1957. A replica of this crocodile has been made as a tourist attraction. The largest living crocodile known is a 7.1 metres (23 ft) long saltwater crocodile, in Orissa, India. It lives in Bhitarkanika Wildlife Sanctuary and in June 2006, was entered in the Guinness Book of World Records.

There is no reliable way of measuring crocodile age, although several techniques are used to derive a reasonable guess. The most common method is to measure lamellar growth rings in bones and teeth—each ring corresponds to a change in growth rate which typically occurs once a year between dry and wet seasons. Bearing these inaccuracies in mind, the oldest crocodilians appear to be the largest species. C. porosus is estimated to live around 70 years on average, and there is limited evidence that some individuals may exceed 100 years. One of the oldest crocodiles recorded died in a zoo in Russia. A male freshwater crocodile at the Australia Zoo is estimated to be 130 years old. He was rescued from the wild by Bob Irwin and Steve Irwin after being shot twice by hunters. As a result of the shootings, this crocodile (known affectionately as "Mr. Freshy") has lost his right eye.

The larger species of crocodiles are very dangerous to humans. The main danger that crocodiles pose is not their ability to run after a person but their ability to strike before the person can react. The Saltwater and Nile Crocodiles are the most dangerous, killing hundreds of people each year in parts of south-east Asia and Africa. Mugger crocodiles and possibly the endangered Black Caiman are also very dangerous to humans. American alligators are less aggressive and rarely assault humans without provocation.

A crocodile is any species belonging to the family Crocodylidae (sometimes classified instead as the subfamily Crocodylinae). The term can also be used more loosely to include all members of the order Crocodilia: i.e. the true crocodiles, the alligators and caimans (family Alligatoridae) and the gharials (family Gavialidae), or even the Crocodylomorpha which includes prehistoric crocodile relatives and ancestors. Crocodiles are large aquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. Crocodiles tend to congregate in freshwater habitats like rivers, lakes, wetlands and sometimes in brackish water. They feed mostly on vertebrates like fish, reptiles, and mammals, sometimes on invertebrates like mollusks and crustaceans, depending on species. They are an ancient lineage, and are believed to have changed little since the time of the dinosaurs. They are believed to be 200 million years old whereas dinosaurs became extinct 65 million years ago; crocodiles survived great extinction events.

Crocodiles are among the more biologically complex reptiles despite their prehistoric look. Unlike other reptiles, they incorporate muscles used for aquatic locomotion into respiration (e.g. M. diaphragmaticus), giving them the functional equivalent of a diaphragm; a cerebral cortex; and a four-chambered heart. Their externalmorphology on the other hand is a sign of their aquatic and predatory lifestyle. A crocodile’s physical traits allow it to be a successful predator. They have a streamlined body that enables them to swim swiftly. Crocodiles also tuck their feet to their sides while swimming, which makes them faster by decreasing water resistance. They have webbed feet which, although not used to propel the animal through the water, allow it to make fast turns and sudden moves in the water or initiate swimming. Webbed feet are an advantage in shallower water where the animals sometimes move around by walking.

Crocodiles have a palatal flap, a rigid tissue at the back of the mouth that blocks the entry of water. The palate has a special path from the nostril to the glottis that bypasses the mouth. The nostrils are closed during submergence. Like other archosaurs, crocodilians are diapsid, although their post-temporal fenestrae are reduced. The walls of the braincase are bony but they lack supratemporal and postfrontal bones. Their tongues are not free but held in place by a membrane which limits movement; as a result, crocodiles are unable to stick out their tongues.

Crocodilian scales have pores that are believed to be sensory, analogous to the lateral line in fishes. They are particularly seen on their upper and lower jaws. Another possibility is that they are secretory, as they produce an oily substance that appears to flush mud off.

Crocodiles are very fast over short distances, even out of water. Since crocodiles feed by grabbing and holding onto their prey, they have evolved sharp teeth for tearing and holding onto flesh, and powerful muscles that close the jaws and hold them shut. These jaws can bite down with immense force, by far the strongest bite of any animal. The crocodile's bite force is more than 5,000 pounds per square inch (340 atm), compared to just 335 pounds per square inch (22.8 atm) for a rottweiler, 400 pounds per square inch (27 atm) for a large great white shark, or 800 pounds per square inch (54 atm) to 1,000 pounds per square inch (68 atm) for a hyena. The jaws are opened, however, by a very weak set of muscles. Crocodiles can thus be subdued for study or transport by taping their jaws or holding their jaws shut with large rubber bands cut from automobile inner tubes. They have limited lateral
(side-to-side) movement in their neck.

Crocodiles are ambush hunters, waiting for fish or land animals to come close, then rushing out to attack. As cold-blooded predators, they have a very slow metabolism, and thus can survive long periods without food. Despite their appearance of being slow, crocodiles are top predators in their environment, and various species have been observed attacking and killing sharks. A famous exception is the Egyptian Plover which is said to enjoy a symbiotic relationship with the crocodile. According to unauthenticated reports, the plover feeds on parasites that infest the crocodile's mouth and the reptile will open its jaws and allow the bird to enter to clean out the mouth.

Many large crocodilians swallow stones (called gastroliths or stomach stones) which may act as ballast to balance their body or assist in crushing food, similar to grit in birds.

Salt glands are present in the tongues of most crocodylids and they have a pore opening on the surface of the tongue. They appear to be similar to those in marine turtles; they seem to be absent in Alligatoridae.

Crocodilians can produce sounds during distress and in aggressive displays. They can also hear well and the tympanic membranes are concealed by flat flaps that may be raised or lowered by muscles. Crocodiles eat fish, birds, mammals and occasionally smaller crocodiles.

Crocodiles are protected in many parts of the world, but they also are farmed commercially. Their hide is tanned and used to make leather goods such as shoes and handbags, whilst crocodile meat is also considered a delicacy.

The most commonly farmed species are the Saltwater and Nile crocodiles, while a hybrid of the Saltwater and the rare Siamese Crocodile is also bred in Asian farms. Farming has resulted in an increase in the Saltwater crocodile population in Australia, as eggs are usually harvested from the wild, so landowners have an incentive to conserve crocodile habitat.

Crocodiles are more closely related to birds and dinosaurs than to most animals classified as reptiles, the three being included in the group Archosauria ('ruling reptiles').

Crocodile embryos do not have sex chromosomes, and unlike humans sex is not determined genetically. Sex is determined by temperature, with males produced at around 31.6 °C, and females produced at slightly lower and higher temperatures.

The average incubation period is around 80 days, and also is dependent upon temperature.Crocodiles may possess a form of homing instinct. Three rogue saltwater crocodiles were relocated 400 kilometres by helicopter in northern Australia but had returned to their original locations within three weeks, based on data obtained from tracking devices attached to the reptiles.

The land speed record for a crocodile is 17 km/h (11 mph) measured in a galloping Australian freshwater crocodile. Maximum speed varies from species to species. Certain types of crocodiles can indeed gallop, including Cuban crocodiles, New Guinea crocodiles, African dwarf crocodiles, and even small Nile crocodiles. The fastest means by which most species can move is a kind of "belly run", where the body moves in a snake-like fashion, limbs splayed out to either side paddling away frantically while the tail whips to and fro. Crocodiles can reach speeds of 10 or 11 km/h (around 7 mph) when they "belly run", and often faster if they're slipping down muddy riverbanks. Another form of locomotion is the "high walk" where the body is raised clear off the ground.

Size greatly varies between species, from the dwarf crocodile to the saltwater crocodile. Species of Palaeosuchus and Osteolaemus grow to an adult size of just 1 metre (3.3 ft) to 1.5 metres (4.9 ft). Larger species can reach over 4.85 metres (15.9 ft) long and weigh well over 1,200 kilograms (2,600 lb). Crocodilians show pronounced sexual dimorphism with males growing much larger and more rapidly than females. Despite their large adult size, crocodiles start their life at around 20 centimetres (7.9 in) long.

Antelope

2009-09-17T16:09:00.000-07:00

Antelope is a term referring to many even-toed ungulate species found in the family Bovidae. The term does not refer to a monophyletic group, as not all members of Bovidae are considered antelope. Instead, the term refers to a ‘miscellaneous’ group within the family encompassing the species which are not cattle, sheep, buffalo, bison, or goats. A group of antelope is called a herd.

Confusingly, the pronghorn antelope of North America is not an antelope, and no antelope species are native to the Americas. The pronghorn is not a member of the family Bovidae, but the family Antilocapridae. True antelope have horns which are unbranched and never shed, while Pronghorns have branching horns, shed annually.

Antelope are even-toed ruminant mammals. There are almost a hundred species of antelope, which vary widely in appearance, strategy, habitat, and range.

Antelope are not a cladistic or taxonomically defined group. The term is used loosely to describe all members of the family Bovidae which do not fall under the category of sheep, cattle, or goat. Usually all species of the Alcelaphinae, Antilopinae, Hippotraginae, Reduncinae, Cephalophinae, many Bovinae, the Grey Rhebok and the Impala are called antelopes.

Most species of antelope are native to Africa, but some originate in Asia as well. The Arabian peninsula is home to the Arabian Oryx and Dorcas gazelle. India is home to the Nilgai, Chinkara and Blackbuck, while Russia and Southeast Asia have the Four-horned Antelope, Tibetan antelope, and Saiga antelope.

Many species of antelope have been imported to other parts of the world, especially the United States, for exotic game hunting. Due to the spectacular leaping and evasive skills of some species, escaped individuals are not unheard of. Texas in particular has high numbers of gaming ranches, as well as habitat and climate that are very hospitable to African plains antelope species. As such, wild populations of Blackbuck Antelope, Gemsbok, and Nilgai have established in Texas, though they are not native to the area.

Antelope exist in a wide range of habitats. Numerically, most exist in the African savannahs. However, there are many species of more secluded forest antelope, as well as the extreme-cold living saiga, desert adapted Arabian oryx, the rocky kopje-living klipspringer and semi-aquatic sitatunga.

Species of forest, woodland or bush tend to be sedentary, but many of the plains species undertake huge migrations. These migrations enable grass-eating species to follow the rains and therefore their food supply. The gnus and gazelles of East Africa perform some of the most impressive mass migratory circuits of all mammals.

All bovids have even-toed hooves, horizontal pupils, ruminating guts, and (in at least the males) bony horns. These basic characteristics, however, mask huge differences in appearance between antelopes, cattle, goats and sheep, and among the antelopes themselves. For example, a male Common Eland can measure 178 cm at the shoulder and weigh almost 950 kg, whereas an adult Royal Antelope may stand only 24 cm at the shoulder and weigh a mere 1.5 kg.

Not surprisingly for animals with long slender yet powerful legs, many antelopes have long strides and can run fast. Some (e.g. Klipspringer) are also adapted to climbing in rock kopjes. Both Dibatags and Gerenuks habitually stand on their two hind legs to reach acacia and other tree foliage. Different antelope have different body types which can affect movement. Duikers are short, bush dwelling antelope that can pick through dense foliage and dive into the shadows rapidly. Gazelles and Springbok are known for their speed and leaping abilities. Even larger antelope, such as Nilgai, Elands, and Kudus, are capable of jumping 8 feet or greater, although their running speed is restricted by their greater mass.

Antelopes have a wide variety of coverings, through most have a dense coat of short fur. In most species, the coat (pelage) is some variation of a brown colour (or several shades of brown); often with white or pale under-bodies. Exceptions include the zebra-marked Zebra Duiker, the grey, black and white Jentink's Duiker and the Black Lechwe. Most of the "spiral-horned" antelopes have pale vertical stripes on their backs. Many desert and sub-desert species are particularly pale, some almost silvery or whitish (e.g. Arabian Oryx); the Beisa and Southern Oryxes have gray and black pelage with vivid black-and-white faces. Common features of various gazelles are a white rump, which flashes a warning to others when they run from danger, and a dark stripe mid-body (the latter feature is also shared by the Springbok and Beira). The Springbok also has a pouch of white brushlike hairs running along its back, which opens up when the animal senses danger, causing the dorsal hairs to stand on end.

Antelopes are ruminants, and thus have well-developed molar teeth, which grind cud (food balls stored in the stomach) into a pulp for further digestion. They have no upper incisors, but rather a hard upper gum pad, against which their lower incisors bite to tear grass stems and leaves.

Like many other herbivores, antelopes rely on keen senses to avoid predators. Their eyes are placed on the sides of their heads, giving them a broad radius of vision with minimal binocular vision. The fact that most species have their pupils elongated horizontally also helps in this respect. Acute senses of smell and hearing, give antelope the ability to perceive danger at night out in the open (when predators are often on the prowl). These same senses play an important role in contact between individuals of the same species: markings on head, ears, legs and rumps are used in such communication—many species "flash" such markings, as well as their tails; vocal communications include loud barks, whistles, "moos" and trumpeting; many species also use scent marking to define their territories or simply to maintain contact with their relatives and neighbors.

Many antelope are sexually dimorphic. In most species, both sexes have horns, but those of males tend to be larger. There is a tendency for males to be larger than the females; however, exceptions in which the females tend to be heavier than the males include the Bush Duiker, Dwarf Antelope, Cape Grysbok and Oribi, all rather small species. A number of species have hornless females (e.g. Sitatunga, Red Lechwe, and Suni). In some species, the males and females have different coloured pelage (e.g. Blackbuck and Nyala).

Size and shape of horns varies immensely. Those of the duikers and dwarf antelopes tend to be simple "spikes", but differ in the angle to the head from backward curved and backward pointing (e.g. Yellow-backed Duiker) to straight and upright (e.g. Steenbok). Other groups have twisted (e.g. Common Eland), spiral (e.g. Greater Kudu), "recurved" (e.g. the reedbucks), lyrate (e.g. Impala), or long, curved (e.g. the oryxes) horns. Horns are not shed and are not made of bone, which distinguishes them from antlers.

Horns are efficient weapons and tend to be better developed in those species where males fight over females (large herd antelope) than in solitary or lekking species. With male-male competition for mates, horns are clashed in combat. It is much more common for males to use their horns against each other than against another species.

The boss of the horns is typically arranged in such a way that two antelope striking at each other's horns cannot crack each other's skulls, making a fight via horn more ritualized than dangerous. Many species have ridges in their horns for at least 2/3 the length of their horns, but these ridges are not a direct indicator of age.

Antelope are often classified by their reproductive behavior.

Forest-dwelling bushbuck.Small antelope, such as dik-diks, tend to be monogamous. They live in a forest environment with patchy resources, and a male is unable to monopolize more than one female due to this sparse distribution. Larger forest species often form very small herds of 2-4 females and 1 male.

Some species such as lechwe pursue a lek breeding system. In this, the males gather on a lekking ground and compete for a small territory, while the females appraise males and choose one with whom to mate.

Large grazing antelope, such as impala or wildebeest form large herds made up of many females and a single breeding male, which excludes all other males, often by combat.

Antelope pursue a number of defense strategies, often dictated by their morphology.

Large antelope that gather in large herds, such as wildebeest or cape buffalo rely on numbers and running speed for protection. In some species, adults will circle around the offspring, protecting them from predators when threatened. Many forest antelope rely on cryptic coloring and good hearing to avoid predators. Forest antelope often have very large ears and a dark or striped coloration. Small antelope, especially duikers, evade predation by jumping into dense bush where the predator cannot pursue. Springboks use a behavior known as stotting to confuse predators.

Fast running gazelles prefer open grassland habitatOpen grassland species have nowhere to hide from predatorsm so they tend to be fast runners. They are agile and have good endurance. These are advantages when pursued by sprint-dependent predators like cheetah, which are the fastest of land animals but tire quickly. Reaction distances vary with predator species and predator behaviour. For example, gazelles may not flee from a lion until it is closer than 200 m (650 ft) lions hunt as a pride or by surprise, usually by stalking, one that can be seen clearly is unlikely to attack. However, sprint-dependent cheetahs will cause gazelles to flee at a range of over 800 m (0.5 mile).

It is difficult to determine how long antelope live in the wild. With the preference of predators towards old and infirm individuals who can no longer sustain peak speeds, few wild prey-animals live as long as their biological potential. In captivity, wildebeest have lived beyond 20 years old, and Impalas have reached their late teens. In the wild, few individuals of prey species live to old age, as the old and weak fall easier prey to their predators; antelopes are no exception to this rule.

Domestication of animals requires certain traits in the animal which antelope do not typically display. Most species are difficult to contain in any density, due to aggression or territoriality of males. Because many have extremely good jumping abilities, providing adequate fencing is a challenge. Also, antelope will consistently display a fear response to perceived predators, such as humans, making them very difficult to herd or handle.

Although antelopes have a diet and rapid growth rate highly suitable for domestication, this tendency to panic and their non-hierarchical social structure explains why not a single one of ninety or so species of antelope has been domesticated.

A wide variety of antelope hybrids have been recorded in zoos, game parks, and wildlife ranches. This is due to either a lack of more appropriate mates in enclosures shared with other species or a misidentification of species. The ease of hybridization shows how closely related some antelope species are. With few exceptions, most hybrid antelope occur only in captivity.

Most hybrids occur between species within the same genus. All reported examples occur within the same sub-family. As with most mammal hybrids, the less closely related the parents, the more likely that the offspring will be sterile.

Bird

2009-08-14T11:23:00.000-07:00

Birds (class Aves) are winged, bipedal, endothermic (warm-blooded), vertebrate animals that lay eggs. There are around 10,000 living species, making them the most numerous tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Birds range in size from the 5 cm (2 in) Bee Hummingbird to the 3 m (10 ft) Ostrich. The fossil record indicates that birds evolved from theropod dinosaurs during the Jurassic period, around 150–200 Ma (million years ago), and the earliest known bird is the Late Jurassic Archaeopteryx, c 155–150 Ma. Most paleontologists regard birds as the only clade of dinosaurs that survived the Cretaceous–Tertiary extinction event approximately 65.5 Ma.

Modern birds are characterised by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. All birds have forelimbs modified as wings and most can fly, with some exceptions including ratites, penguins, and a number of diverse endemic island species. Birds also have unique digestive and respiratory systems that are highly adapted for flight. Some birds, especially corvids and parrots, are among the most intelligent animal species; a number of bird species have been observed manufacturing and using tools, and many social species exhibit cultural transmission of knowledge across generations.

Many species undertake long distance annual migrations, and many more perform shorter irregular movements. Birds are social; they communicate using visual signals and through calls and songs, and participate in social behaviours including cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have breeding systems that are polygynous ("many females") or, rarely, polyandrous ("many males"). Eggs are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching.

Many species are of economic importance, mostly as sources of food acquired through hunting or farming. Some species, particularly songbirds and parrots, are popular as pets. Other uses include the harvesting of guano (droppings) for use as a fertiliser. Birds figure prominently in all aspects of human culture from religion to poetry to popular music. About 120–130 species have become extinct as a result of human activity since the 17th century, and hundreds more before then. Currently about 1,200 species of birds are threatened with extinction by human activities, though efforts are underway to protect them.

Birds live and breed in most terrestrial habitats and on all seven continents, reaching their southern extreme in the Snow Petrel's breeding colonies up to 440 kilometres (270 mi) inland in Antarctica. The highest bird diversity occurs in tropical regions. It was earlier thought that this high diversity was the result of higher speciation rates in the tropics, however recent studies found higher speciation rates in the high latitudes that were offset by greater extinction rates than in the tropics. Several families of birds have adapted to life both on the world's oceans and in them, with some seabird species coming ashore only to breed and some penguins have been recorded diving up to 300 metres (980 ft).

Many bird species have established breeding populations in areas to which they have been introduced by humans. Some of these introductions have been deliberate; the Ring-necked Pheasant, for example, has been introduced around the world as a game bird. Others have been accidental, such as the establishment of wild Monk Parakeets in several North American cities after their escape from captivity. Some species, including Cattle Egret, Yellow-headed Caracara and Galah, have spread naturally far beyond their original ranges as agricultural practices created suitable new habitat.

Birds have two sexes: male and female. The sex of birds is determined by the Z and W sex chromosomes, rather than by the X and Y chromosomes present in mammals. Male birds have two Z chromosomes (ZZ), and female birds have a W chromosome and a Z chromosome (WZ).

In nearly all species of birds, an individual's sex is determined at fertilization. However, one recent study demonstrated temperature-dependent sex determination among Australian Brush-turkeys, for which higher temperatures during incubation resulted in a higher female-to-male sex ratio.

Brood parasitism, in which an egg-layer leaves her eggs with another individual's brood, is more common among birds than any other type of organism. After a parasitic bird lays her eggs in another bird's nest, they are often accepted and raised by the host at the expense of the host's own brood. Brood parasites may be either obligate brood parasites, which must lay their eggs in the nests of other species because they are incapable of raising their own young, or non-obligate brood parasites, which sometimes lay eggs in the nests of conspecifics to increase their reproductive output even though they could have raised their own young. One hundred bird species, including honeyguides, icterids, estrildid finches and ducks, are obligate parasites, though the most famous are the cuckoos. Some brood parasites are adapted to hatch before their host's young, which allows them to destroy the host's eggs by pushing them out of the nest or to kill the host's chicks; this ensures that all food brought to the nest will be fed to the parasitic chicks.

Governments and conservation groups work to protect birds, either by passing laws that preserve and restore bird habitat or by establishing captive populations for reintroductions. Such projects have produced some successes; one study estimated that conservation efforts saved 16 species of bird that would otherwise have gone extinct between 1994 and 2004, including the California Condor and Norfolk Island Green Parrot.

Reptiles

2009-08-04T18:12:00.000-07:00

Reptiles, or members of the class Reptilia, are air-breathing, cold-blooded amniotes that have skin covered in scales or scutes as opposed to hair or feathers. They are tetrapods (having or having descended from vertebrates with four limbs) and lay amniote eggs, whose embryos are surrounded by the amnion membrane. Modern reptiles inhabit every continent with the exception of Antarctica, and four living orders are currently recognized:

Crocodilia (crocodiles, gavials, caimans, and alligators): 23 species

Sphenodontia (tuatara from New Zealand): 2 species

Squamata (lizards, snakes, and amphisbaenids, worms) approximately 7,900 species

Testudines (turtles and tortoises): approximately 300 species

The majority of reptile species are oviparous (egg-laying) although certain species of squamates are capable of giving live birth. This is achieved, either through ovoviviparity (egg retention), or viviparity (offspring born without use of calcified eggs). Many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals with some providing initial care for their hatchlings. Extant reptiles range in size from a tiny gecko, Sphaerodactylus ariasae, that grows to only 1.6 cm (0.6 in), to the saltwater crocodile that may reach 6 m in length and weigh over 1,000 kg. The science dealing with reptiles is called
herpetology.

The reptiles were from the outset of classification grouped with the amphibians. Linnaeus working from species poor Sweden where the common adder and grass Snake are often found hunting in water, included all reptiles and amphibians in class "III - Amphibia" in his Systema Naturae. The terms "reptile" and "amphibian" were largely interchangeable, "reptiles" being preferred by the French. Josephus Nicolaus Laurenti were the first to formally use the term "Reptilia" for an expanded, though basically similar selection of reptiles and amphibians to that of Linnaeus. Not until the turn of the century did it become clear that reptiles and amphibians are in fact quite different animals, and Pierre André Latreille erected the class Batracia for the latter, dividing the tetrapods into the four familiar classes of reptiles, amphibians, birds and mammals.

The origin of the reptiles lays about 320-310 million years back, in the steaming swamps of the late Carboniferous, when the first reptiles evolved from advanced reptilomorph labyrinthodonts. The oldest traces of reptiles is a series of footprints from the fossil strata of Nova Scotia, dated to 315 million years old. The tracks are attributed to Hylonomus, the oldest known reptile in the biological sense of the word. It was a small, lizard-like animal, about 20 to 30 cm (8-12 inche) long, with numerous sharp teeth indicating an insectivorous diet. Other examples include Westlothiana (for the moment considered to be more related to amphibians than amniotes) and Paleothyris, both of similar build and presumably habit. One of the best known early reptiles is Mesosaurus, a genus of early reptiles from the early Permian that had returned to water, living off fish. The earliest reptiles were largely overshadowed by bigger labyrinthodont amphibians such as Cochleosaurus, and remained a small, inconspicuous part of the fauna until after the small ice age at the end of the Carboniferous.

The first reptiles are categorized as Anapsids, having a solid skull with holes only for nose, eyes, spinal cord, etc. Turtles are believed by some to be surviving Anapsids, as they also share this skull structure, but this point has become contentious lately, with some arguing that turtles reverted to this primitive state in order to improve their armor. Both sides have strong evidence, and the conflict has yet to be resolved.

Very early after the first reptiles appeared, two branches split off. One lead to the Synapsida (the "mammal-like reptiles" or "stem mammals"), having two openings in the skull roof behind the eyes high , the other group, Diapsida, possessed a pair of holes in their skulls behind the eyes, along with a second pair located higher on the skull.

The function of the holes in bout groups was to lighten the skull and give room for the jaw muscles to move, allowing for a more powerful bite. The diapsids and later anapsids are classed as the "true reptiles", the Sauropsida.

With the close of the Carboniferous, reptiles became the dominant tetrapod fauna. While the terrestrial reptilomorph labyrinthodonts still existed, the mammal-like reptiles evolved the first terrestrial megafauna in the form of pelycosaurs like Edaphosaurus and the carnivorous Dimetrodon. In the mid-Permian the climate turned dryer, resulting in a faunal turnover. The primitive pelycosaurs where replaced by the more advanced therapsids.

The anapsid reptiles, with their massive skulls without postorbital holes, continued and flourished throughout the Permian. The pareiasaurs reached giant proportions in the late Permian, eventually disappearing at the close of the period (the turtles being possible survivors).

Early in the period, the diapside reptiles split into two lineages, the lepidosaurs (forefathers of modern snakes, lizards, and tuataras). The group remained lizard-like and relatively small and inconspicuous during the whole periode.

The close of the Permian saw the greatest mass extinction known (see the Permian–Triassic extinction event). Most of the earlier anapsid/synapsid megafauna disappeared, making room for the archosauromorph diapsids. The archosaurs was characterized by elongated hind-legs and an erect pose, the early forms looking somewhat like long legged crocodiles. The archosaurs became the dominant group during the Triassic, developing into the well known dinosaurs and pterosaurs, as well as crocodiles and phytosaurs. Some of the dinosaurs developed into the largest land animals ever to have lived, making the Mesozoic popularly known as the "Age of Reptiles". The dinosaurs also deveoped smaller forms, including the feather-bearing smaller theropds. In the mid Jurassic, these gave rise to the first birds.

The lepidosauromorph diapsids may have been ancestral to the sea reptiles. Developing into the ichthyosaurs and sauropterygians, they came to dominate the Mesozoic seas.

The Therpasids came under increasing pressure from the archosaurs the early Mesozoic and developed into increasingly smaller and more nocturnal forms, the first mammals being the only survivors of the line by late Jurassic.

The close of the Cretacious saw the demise of the Mesozoic reptilian megafauna (see the Cretaceous–Tertiary extinction event). Of the large marine reptiles, only the sea turtles are left, and of the dinosaurs, only the small feathered theropods survived in the form of birds. The major surviving reptilian line is the lepidosaurs, of which the snakes are currently the most numerous and widespread representatives. The end of the “Age of Reptiles”, opened up for the “Age of Mammals”. Despite this, reptiles are still a major fauna component, particularly in tropical climates. There are about 8200 extant species of reptiles (whereof almost half are snakes), compared to 5400 species of mammals (of which two/thirds are rodents and bats). The most numerous modern group with reptilian roots are the birds, with over 9000 species.

Most reptiles have a three-chamber heart consisting of two atria, one variably-partitioned ventricle, and two aorta that go the systemic circulation. The degree of mixing of oxygenated and deoxygenated blood in the three-chamber heart is variable depending on the species and physiological state. Under different conditions, deoxygenated blood can be shunted back to the body or oxygenated blood can be shunted back to the lungs. This variation in blood flow has been hypothesized to allow more effective thermoregulation and longer diving times for aquatic species, but has not been shown to be a fitness advantage.

There are some interesting exceptions to the general physiology. For instance, crocodilians have an anatomically four-chambered heart, but also have two systemic aorta and are therefore capable only of bypassing their pulmonary circulation. Also, some snake and lizard species (e.g., monitor lizards and pythons) have three-chamber hearts that become functional four-chamber hearts during contraction. This is made possible by a muscular ridge that subdivides the ventricle during ventricular diastole and completely divides it during ventricular systole.

Because of this ridge, some of these squamates are capable of producing ventricular pressure differentials that are equivalent to those seen in mammalian and avian hearts.

All reptiles breathe using lungs. Aquatic turtles have developed more permeable skin, and some species have modified their cloaca to increase the area for gas exchange (Orenstein, 2001). Even with these adaptations, breathing is never fully accomplished without lungs. Lung ventilation is accomplished differently in each main reptile group. In squamates, the lungs are ventilated almost exclusively by the axial musculature. This is also the same musculature that is used during locomotion. Because of this constraint, most squamates are forced to hold their breath during intense runs. Some, however, have found a way around it.

Varanids, and a few other lizard species, employ buccal pumping as a complement to their normal "axial breathing." This allows the animals to completely fill their lungs during intense locomotion, and thus remain aerobically active for a long time. Tegu lizards are known to possess a proto-diaphragm, which separates the pulmonary cavity from the visceral cavity.

While not actually capable of movement, it does allow for greater lung inflation, by taking the weight of the viscera off the lungs (Klein et al., 2003). Crocodilians actually have a muscular diaphragm that is analogous to the mammalian diaphragm. The difference is that the muscles for the crocodilian diaphragm pull the pubis (part of the pelvis, which is movable in crocodilians) back, which brings the liver down, thus freeing space for the lungs to expand.

This type of diaphragmatic setup has been referred to as the "hepatic piston."

How turtles and tortoises breathe has been the subject of much study. To date, only a few species have been studied thoroughly enough to get an idea of how turtles do it. The results indicate that turtles & tortoises have found a variety of solutions to this problem. The problem is that most turtle shells are rigid and do not allow for the type of expansion and contraction that other amniotes use to ventilate their lungs. Some turtles such as the Indian flapshell (Lissemys punctata) have a sheet of muscle that envelops the lungs. When it contracts, the turtle can exhale. When at rest, the turtle can retract the limbs into the body cavity and force air out of the lungs. When the turtle protracts its limbs, the pressure inside the lungs is reduced, and the turtle can suck air in. Turtle lungs are attached to the inside of the top of the shell (carapace), with the bottom of the lungs attached (via connective tissue) to the rest of the viscera. By using a series of special muscles (roughly equivalent to a diaphragm), turtles are capable of pushing their viscera up and down, resulting in effective respiration, since many of these muscles have attachment points in conjunction with their forelimbs (indeed, many of the muscles expand into the limb pockets during contraction). Breathing during locomotion has been studied in three species, and they show different patterns. Adult female green sea turtles do not breathe as they crutch along their nesting beaches. They hold their breath during terrestrial locomotion and breathe in bouts as they rest. North American box turtles breathe continuously during locomotion, and the ventilation cycle is not coordinated with the limb movements (Landberg et al., 2003). They are probably using their abdominal muscles to breathe during locomotion. The last species to have been studied is red-eared sliders, which also breathe during locomotion, but they had smaller breaths during locomotion than during small pauses between locomotor bouts, indicating that there may be mechanical interference between the limb movements and the breathing apparatus. Box turtles have also been observed to breathe while completely sealed up inside their shells.

Most reptiles lack a secondary palate, meaning that they must hold their breath while swallowing. Crocodilians have evolved a bony secondary palate that allows them to continue breathing while remaining submerged (and protect their brains from getting kicked in by struggling prey). Skinks (family Scincidae) also have evolved a bony secondary palate, to varying degrees. Snakes took a different approach and extended their trachea instead.

Their tracheal extension sticks out like a fleshy straw, and allows these animals to swallow large prey without suffering from asphyxiation.Reptilian skin is covered in a horny epidermis, making it watertight and enable reptiles to live on dry land, in contrast to the amphibians. Compared to mammals, reptilian skin is rather thin, and lack the thick dermal layer that produces leather in mammals. Exposed parts of reptiles are protected by scales or scutes, sometimes with a bony base, forming armour. In turtles, the body is hidden inside a hard shell composed on fused scutes. In the lepidosaurians like lizards and snakes, the whole skin is covered in epidermal scales. Such scales where once thought to be typical of the class Reptilia as a whole, but are actually found only in lepidosaurians. The scales found in turtles and crocodiles are of dermal origin rather than epidermal, and are properly termed scutes.

Excretion is performed mainly by two small kidneys. In diapsids, uric acid is the main nitrogenous waste product; turtles, like mammals, mainly excrete urea.

Unlike the kidneys of mammals and birds, reptile kidneys are unable to produce liquid urine more concentrated than their body fluid. This is because they lack a specialized structure present in the nephrons of birds and mammals, called a Loop of Henle. Because of this, many reptiles use the colon to aid in the reabsorption of water. Some are also able to take up water stored in the bladder. Excess salts are also excreted by nasal and lingual salt glands in some reptiles.

Most reptiles are carnivorous and have rather simple and not overly long guts, meat being fairly simple to break down and digest. Digestion is slower than in mammals, reflecting about the fact that they can not divide and masticate their food like mammals do, and their lower metabolism. Being cold blooded their energy requirement is about a 5th to a 10th of that of a mammal of the same size. Large reptiles like crocodiles and the large constrictors can basically live from a single large meal for months, digesting it slowly.

While modern reptiles are predominately carnivorous, this has not always been so. During the early history of reptiles, several groups produced big-bodied herbivorous megafauna, in the Paleozoic the Pareiasaurs and the synapsid Dicynodonts, and in the Mesozoic several lines of Dinosaurs. Today the turtles are the only predominantly herbivorous reptile group, but several lines of agams and iguanas have developed to live wholly or partly from plants.

Herbivorous reptiles face the same problems of mastication as herbivorous mammals, but lacking the complex mammal teeth, quite a few species swallow rocks and pebbles to aid in digestion, so called gastrolithes. The rocks are washed around in the stomach helping to grind up plant matter. Fossil gastrolithes has also been found associated with sauropods. Sea turtles, crocodiles and marine iguanas also use the gastrolithes as ballast, helping them to dive.

The reptilian nervous system contains the same basic part of the amphibian brain, but the reptile cerebrum and cerebellum are slightly larger. Most typical sense organs are well developed with certainexceptions most notably the snake's lack of external ears (middle and inner ears are present). There are twelve pairs of cranial nerves.

Reptiles are not generally considered particularly intelligent when compared to mammals and birds. Their brains fall well below those of mammals in size relative to the body, the encephalisation quotient being about one tenth of that of mammals. The crocodiles have brains in the higher size range and show a fairly complex social structure.

Larger lizards like the monitors are known to exhibit complex behaviour, including cooporation. The Komodo dragon is known to engage in play.

Most reptiles are diurnal animals. The vision is typically adapted to daylight condition, with colour vision and advanced visual depth perception compared to amphibians and most mammals. In some species vision is reduced, such as blindsnakes. Some snakes have extra sets of visual organs (in the loosest sense of the word) in the form of pits sensitive to infrared radiation (heat). Such heat sensitive pits are particularly well developed in the pit vipers, but also found in boas and pythons. These allows the snakes to sense the body heat from birds and mammals, making pitvipers able to hunt rodents in the dark.

Most reptiles reproduce sexually, though some are capable of asexual reproduction. All reproductive activity occurs with the cloaca, the single exit/entrance at the base of the tail where waste is also eliminated. Tuataras lack copulatory organs, so the male and female simply press their cloacas together as the male excretes sperm.

Most reptiles, however, have copulatory organs, which are usually retracted or inverted and stored inside the body.

In turtles and crocodilians, the male has a single median penis, while squamates including snakes and lizards possess a pair of hemipenes.

Most reptiles lay amniotic eggs covered with leathery or calcareous shells. An amnion, chorion, and allantois are present during embryonic life. There are no larval stages of development. Viviparity and ovoviviparity have only evolved in Squamates, and a substantial fraction of the species utilize this mode of reprduction, including all boas and most vipers. The degree of viviparity varies: some species simply retain the eggs until just before hatching, others provide maternal nourishment to supplement the yolk, and yet others lack any yolk and provide all nutrients via a placenta.

Asexual reproduction has been identified in squamates in six families of lizards and one snake.

In some species of squamates, a population of females are able to produce a unisexual diploid clone of the mother. This asexual reproduction called parthenogenesis occurs in several species of gecko, and is particularly widespread in the teiids (especially Aspidocelis) and lacertids (Lacerta). In captivity, Komodo dragons (varanidae) have reproduced by parthenogenesis.

Parthenogenetic species are also suspected to occur among chameleons, agamids, xantusiids, and typhlopids.

Primates

2009-08-04T14:34:00.000-07:00

A primate is a member of the biological order Primates, the group that contains lemurs, the Aye-aye, lorisids, galagos, tarsiers, monkeys, and apes, with the last category including great apes. With the exception of humans, who inhabit every continent on Earth, most primates live in tropical or subtropical regions of the Americas, Africa and Asia. Primates range in size from the Pygmy Mouse Lemur weighing only 30 grams (1.1 oz) to the Mountain Gorilla weighing 200 kilograms (440 lb). According to fossil evidence, the primitive ancestors of primates may have existed in the late Cretaceous period around 65 million years ago, and the oldest known primate is the Late Paleocene Plesiadapis, c. 55–58 million years ago. Molecular clock studies suggest that the primate branch may be even older, originating in the mid-Cretaceous period around 85 mya.

The Primates order has traditionally been divided into two main groupings: prosimians and simians. Prosimians have characteristics most like those of the earliest primates, and included the lemurs of Madagascar, lorisiforms, Aye-aye and tarsiers. Simians included the monkeys and apes. More recently, taxonomists have created the suborder Strepsirrhini, or "curly-nosed" primates, to include non-tarsier prosimians and the suborder Haplorrhini, or "dry-nosed" primates, to include tarsiers and the simians. Simians are divided into two groups: the platyrrhines ("flat nosed") or New World monkeys of South and Central America and the catarrhine ("narrow nosed") monkeys of Africa and southeastern Asia. The New World monkeys include the capuchin, howler and squirrel monkeys, and the catarrhines include the Old World monkeys (such as baboons and macaques) and the apes. Humans are the only catarrhines that have spread outside of Africa, South Asia, and East Asia, although fossil evidence shows many species once existed in Europe as well.

Considered generalist mammals, primates exhibit a wide range of characteristics. Some primates (including some great apes and baboons) do not live primarily in trees, but all species possess adaptations for climbing trees.

Locomotion techniques used include leaping from tree to tree, walking on two or four limbs, knuckle-walking, and swinging between branches of trees (known as brachiation). Primates are characterized by their large brains, relative to other mammals, as well as an increased reliance on stereoscopic vision at the expense of smell, the dominant sensory system in most mammals. These features are most significant in monkeys and apes, and noticeably less so in lorises and lemurs.

Three-color vision has developed in some primates. Most also have opposable thumbs and some have prehensile tails. Many species are sexually dimorphic, which means males and females have different physical traits, including body mass, canine tooth size, and coloration. Primates have slower rates of development than other similarly sized mammals, and reach maturity later but have longer lifespans. Some species live in solitude, others live in male–female pairs, and others live in groups of up to hundreds of members.

The primate lineage is thought go back to at least 65 mya, even though the oldest known primate from the fossil record is Plesiadapis (c. 55–58 mya) from the Late Paleocene. Other studies, including molecular clock studies, have estimated the origin of the primate branch to have been in the mid-Cretaceous period, around 85 mya.

In modern cladistic reckonings, the Primates order is monophyletic. The suborder Strepsirrhini, the curly-nosed or "wet-nosed" primates, is generally thought to have split off from the primitive primate line about 63 mya (million years ago), although earlier dates are also supported. The seven strepsirhine families are the four related lemur families and the three remaining families that include the Aye-aye, the lorisids, and the galagos. Older classification schemes wrap the Lepilemuridae into the Lemuridae and the Galagidae into the Lorisidae, yielding a three-two family split instead of the four-three split as presented here. During the Eocene, most of the northern continents were dominated by two groups, the adapiforms and the omomyids. The former is considered a member of Strepsirrhini, but it does not have a toothcomb like modern lemurs; recent analysis has suggested Darwinius masillae fits into this grouping. The latter was related closely to tarsiers, monkeys, and apes. It is unclear exactly how these two groups relate to extant primates. Omomyids perished about 30 mya, while Adapids survived until about 10 mya.

According to genetic studies, the lemurs of Madagascar diverged from the lorisiforms approximately 75 mya. These studies, as well as chromosomal and molecular evidence, also show that lemurs are more closely related to each other than to other strepsirrhine primates. However, Madagascar split from Africa at 160 mya and from India at 90 mya.

For lemurs to be more closely related to each other than other strepsirrhine primates, it is thought that a very small ancestral population came to Madagascar via a single rafting event between 50 and 80 million years ago.

Other colonization options have been examined, such as multiple colonizations from Africa and India, but none are supported by the genetic and molecular evidence.

Until recently the Aye-aye has been difficult to place within Strepsirrhini. Theories had been proposed that its family, Daubentoniidae, was either a lemuriform primate (meaning its ancestors split from lemur line more recently than the lemurs and lorises split) or a sister group to all the other strepsirrhines. In 2008, the Aye-aye family (Daubentoniidae) was confirmed to be a lemuriform and descended from the same ancestral lemur population that rafted to the island, it is contained within the Chiromyiformes infraorder, forming a sister clade to the lemurs.

The suborder Haplorrhini, the simple-nosed or "dry-nosed" primates, is composed of two sister clades. The prosimian tarsiers in family Tarsiidae (monotypic in its own infraorder Tarsiiformes), represent the most primitive division at about 58 mya. The Simiiformes infraorder emerged about 40 mya, and contains the two clades: the parvorder Platyrrhini that developed in South America and contains New World monkeys, and the parvorder Catarrhini that developed in Africa and contains the Old World monkeys, humans and the other apes. A third clade, which included the eosimiids, developed in Asia but went extinct millions of years ago.

Like the lemurs, the New World monkeys have unclear origins. Molecular sequence studies based on concatenated sequences have yielded wide variations in the estimated date of the divergence between platyrrhines and catarrhines, ranging from 33 to 70 mya, while studies based on mitochondrial sequences suggest a more consistent date of 35 mya.

It has been postulated that there is a single origin for the anthropoids in Africa some migrated and subsequently speciation occurred. It is possible that the anthropoid primates traversed the Atlantic ocean during the Eocene, facilitated by Atlantic Ocean ridges and a lowered sea level, then island-hopped to South America. Once again, a rafting event may explain this transoceanic colonization. Due to continental drift, the young Atlantic Ocean was not nearly as wide as it is today, and research suggests that a small 1 kg (2.2 lb) primate could have survived 13 days on a raft of vegetation. Given estimated current and wind speeds, this would have provided enough time to make the voyage between the continents.

Apes and monkeys spread from Africa into Europe and Asia starting in the Miocene. Soon after, the lorises and tarsiers made the same journey. The first hominid fossils were discovered in Northern Africa and date back 5–8 mya. Old World monkeys disappeared from Europe about 1.8 mya. Some molecular and fossil studies generally show that modern humans originated in Africa 100–200 tya (thousand years ago).

Although primates are well studied in comparison to other animal groups, several new species have been recently discovered; genetic tests on some populations have revealed previously unrecognised species. Primate Taxonomy listed about 350 species of primates in 2001, the author, Colin Groves, increased that number to 376 for his contribution to the third edition of Mammal Species of the World (MSW3). However, MSW3 falls short of current understanding as its collection was completed in 2003; a number of publications have since pushed the number to 424 species and 658 species and subspecies. Notable new species not listed in MSW3 include the Bemaraha Woolly Lemur (Avahi cleesei, named after British actor and lemur enthusiast John Cleese) and the GoldenPalace.com Monkey (whose name was put up for auction).

Primate hybrids usually arise in captivity, but there have also been examples in the wild. Hybridization occurs where two species' range overlap to form hybrid zones; hybrids may be created by humans when animals are placed in zoos or due to environmental pressures such as predation. Intergeneric hybridizations, hybrids of different genera, have also been found in the wild. Although they belong to genera that have been distinct for several million years, interbreeding still occurs between the Gelada and the Hamadryas Baboon.

Primates have forward-facing eyes on the front of the skull; binocular vision allows accurate distance perception, useful for the brachiating ancestors of all great apes. There is a bony ridge above the eye sockets; this ridge reinforces weaker bones in the face which are put under strain during chewing. Strepsirrhines have a postorbital bar, a bone which runs around the eye socket, to protect their eyes; in contrast, the higher primates, haplorrhines, have evolved fully enclosed sockets.

The primate skull has a large domed cranium which is particularly prominent in anthropoids. The cranium protects the large brain, a distinguishing characteristic of this group. The endocranial volume (the volume within the skull) is three times greater in humans than in the greatest non-human primate, reflecting a larger brain size.

The mean endocranial volume is 1201 cubic centimeters in humans, 469 cm3 in gorillas, 400 cm3 in chimpanzees and 397 cm3 in orangutans. The primary evolutionary trend of primates has been the elaboration of the brain, in particular the neocortex (a part of the cerebral cortex), which is involved with sensory perception, generation of motor commands, spatial reasoning, conscious thought and, in humans, language. While other mammals rely heavily on their sense of smell, the arboreal life of primates has led to a tactile, visually dominant sensory system, a reduction in the olfactory region of the brain and increasingly complex social behavior.

Primates generally have five digits on each limb (pentadactyly), with keratin nails on the end of each finger. The bottom sides of the hands and feet have sensitive pads on the fingertips. Most have opposable thumbs, a characteristic primate feature; however, opposing thumbs are not limited to this order (opossums, for example, also have them). Thumbs allow some species to use tools. In primates, the combination of opposing thumbs, short fingernails (rather than claws) and long, inward-closing fingers is a relic of the ancestral practice of gripping branches, and has, in part, allowed some species to develop brachiation (swinging by the arms from tree limb to tree limb) as a significant means of transportation. Prosimians have clawlike nails on the second toe of each foot, called toilet-claws, which they use for grooming.

The primate collar bone is retained as prominent element of the pectoral girdle; this allows the shoulder joint broad mobility. Apes have more mobile shoulder joints and arms due to the dorsal position of the scapula, broad ribcages that are flatter front-to-back, and a shorter, less mobile spine compared to Old World monkeys (with lower vertebrae greatly reduced, resulting in tail loss in some species). Old World monkeys are unlike apes in that most have tails. The only primate family with prehensile tails are the New World Atelids, including the howler, spider and woolly monkeys.

Primates show an evolutionary trend towards a reduced snout. Technically, Old World monkeys are distinguished from New World monkeys by the structure of the nose, and from apes by the arrangement of their teeth. In New World monkeys the nostrils face sideways; in Old World monkeys, they face downwards. There is a considerably varied dental pattern in primates and although some have lost most of their incisors, all retain at least one lower incisor.

In most strepsirhines, the lower incisors and canines form a toothcomb, which is used in grooming and sometimes foraging, and the first lower premolar is shaped like a canine. Old World monkeys have eight premolars, compared with twelve in New World monkeys. The Old World species are divided into apes and monkeys depending on the number of cusps on their molars; apes have five, Old World monkeys have four, although humans may have 4 or 5. The main hominid molar cusp (hypocone) evolved in early primate history, while the cusp of the corresponding primitive lower molar (paraconid) was lost. Prosimians are distinguished by their immobilized upper lips, the moist tip of their nose and forward-facing lower front teeth.

The evolution of color vision in primates is unique among most eutherian mammals. While the remote vertebrate ancestors of the primates possessed three color vision (trichromaticism), the nocturnal, warm-blooded, mammalian ancestors lost one of three cones in the retina during the Mesozoic period. Fish, reptiles and birds are therefore trichromatic or tetrachromatic while all mammals, with the exception of some primates and marsupials, are dichromats or monochromats (totally color blind). Nocturnal primates, such as the night monkeys and bush babies, are often monochromatic. Catarrhines are routinely trichromatic due to a gene duplication of the red-green opsin gene at the base of their lineage, 30 to 40 million years ago. Platyrrhines, on the other hand, are trichromatic in a few cases only. Specifically, individual females must be heterozygous for two alleles of the opsin gene (red and green) located on the same locus of the X chromosome. Males, therefore, can only be dichromatic, while females can be either dichromatic or trichromatic. Color vision in strepsirrhines is not as well understood; however, research indicates a range of color vision similar to that found in platyrrhines.

Like catarrhines, Howler monkeys (a family of platyrrhines) show routine trichromatism that has been traced to an evolutionarily recent gene duplication. Howler monkeys are one of the most specialized leaf-eaters of the New World monkeys; fruits are not a major part of their diet, and the type of leaves they prefer to consume (young, nutritive, and digestible) are detectable only by a red-green signal. Field work exploring the dietary preferences of howler monkeys suggests that routine trichromaticism was environmentally selected for.

Sexual dimorphism, the variation between individuals of different sex in the same species, is often exhibited in simians, though to a greater degree in Old World species (apes and some monkeys) than New World species. Recent studies involve comparing DNA to examine both the variation in the expression of the dimorphism among primates and the fundamental causes of sexual dimorphism. Primates usually have dimorphism in body mass and canine tooth size along with pelage and skin color. The dimorphism can be attributed to and affected by different factors, including mating system, size, habitat and diet.

Comparative analyses have generated a more complete understanding of the relationship between sexual selection, natural selection, and mating systems in primates. Studies have shown that dimorphism is the product of changes in both male and female traits. Ontogenetic scaling, where relative extension of a common growth trajectory occurs, may give some insight into the relationship between sexual dimorphism and growth patterns. Some evidence from the fossil record suggests that there was convergent evolution of dimorphism, and some extinct hominids probably had greater dimorphism than any living primate.

Primate species move by brachiation, bipedalism, leaping, arboreal and terrestrial quadrupedalism, climbing, knuckle-walking or by a combination of these methods. Several prosimians are primarily vertical clinger and leapers.

These include many bushbabies, all indriids (i.e., sifakas, avahis and indris), sportive lemurs, and all tarsiers. Other prosimians are arboreal quadrupeds and climbers. Some are also terrestrial quadrupeds, while some are leapers. Most monkeys are both arboreal and terrestrial quadrupeds and climbers. Gibbons, muriquis and spider monkeys all use brachiation extensively. Woolly monkeys also sometimes brachiate. Orangutans use a similar form of locomotion called quadramanous climbing, in which they use their arms and legs to carry their heavy bodies through the trees. Chimpanzees and gorillas knuckle walk, and can move bipedally for short distances. Although numerous species, such as the Australopithecines and early hominids, have exhibited fully bipedal locomotion, humans are the only extant species with this trait.

Several species of primates are known to associate in the wild. Some of these associations have been extensively studied. In the Tai Forest of Africa several species coordinate anti-predator behavior. These include the Diana Monkey, Campbell's Mona Monkey, Lesser Spot-nosed Monkey, Western Red Colobus, King Colobus and Sooty Mangabey, which coordinate anti-predator alarm calls. Among the predators of these monkeys is the Common Chimpanzee.

The Red-tailed Monkey associates with several species, including the Western Red Colobus, Blue Monkey, Wolf's Mona Monkey, Mantled Guereza, Black Crested Mangabey and Allen's Swamp Monkey. Several of these species are predated on by the Common Chimpanzee.

In South America, squirrel monkeys associate with capuchin monkeys. This may have more to do with foraging benefits to the squirrel monkeys rather than anti-predation benefits.

Primates have advanced cognitive abilities: some make tools and use them to acquire food and for social displays; some have sophisticated hunting strategies requiring cooperation, influence and rank; they are status conscious, manipulative and capable of deception; they can recognise kin and conspecifics; and they can learn to use symbols and understand aspects of human language including some relational syntax and concepts of number and numerical sequence.

Research in primate cognition explores problem solving, memory, social interaction, a theory of mind, and numerical, spatial, and abstract concepts.

Lemurs, lorises, tarsiers, and New World monkeys rely on olfactory signals for many aspects of social and reproductive behavior. Specialized glands are used to mark territories with pheromones, which are detected by the vomeronasal organ; this process forms a large part of the communication behavior of these primates. In Old World monkeys and apes this ability is mostly vestigial, having regressed as trichromatic eyes evolved to become the main sensory organ. Primates also use vocalizations, gestures, and facial expressions to convey psychological state.

Primates have slower rates of development than other mammals. All non-human primate infants are breastfed by their mothers and rely on them for grooming and transportation. In some species, infants are protected and transported by males in the group, particularly males who may be their fathers. Other relatives of the infant, such as siblings and aunts, may participate in its care as well. Most primate mothers cease ovulation while breastfeeding an infant; once the infant is weaned the mother can reproduce again. This often leads to weaning conflict with infants who attempt to continue breastfeeding.

Primates have a longer juvenile period between weaning and sexual maturity than other mammals of similar size. During the juvenile period, primates are more susceptible than adults to predation and starvation; they gain experience in feeding and avoiding predators during this time they learn social and fighting skills, often through playing.

Primates, especially females, have longer lifespans than other similarly sized mammals.

Whale

2009-07-28T19:21:00.000-07:00

Whales are marine mammals of order Cetacea which are neither dolphins—members, in other words, of the families Delphinidae or Platanistoidae—nor porpoises. They include the blue whale, the largest living animal. Orcas, colloquially referred to as "killer whales", and pilot whales have whale in their name but for the purpose of biological classification they are actually dolphins. For centuries whales have been hunted for meat and as a source of valuable raw materials. By the middle of the 20th century, large-scale industrial whaling had left many
species seriously endangered.

All cetaceans, including whales, dolphins and porpoises, are descendants of land-living mammals of the Artiodactyl order (even-toed ungulate animals). Both cetaceans and artiodactyl are now classified under the super-order Cetartiodactyla which includes both whales and hippopotamuses. In fact, whales are the closest living relatives of hippos; they evolved from a common ancestor at around 54 million years ago. Whales entered the water roughly 50 million years ago. Cetaceans are divided into two suborders:

The baleen whales are characterized by baleen, a sieve-like structure in the upper jaw made of keratin, which they use to filter plankton from the water. They are the largest suborder of whale.

The toothed whales have teeth and prey on fish, squid, or both. An outstanding ability of this group is to sense their surrounding environment through echolocation.

Like all mammals, whales breathe air into lungs, are warm-blooded, feed their young milk from mammary glands, and have some hair, although very little.

The body is fusiform. The forelimbs, also called flippers, are paddle-shaped. The end of the tail holds the fluke, or tail fins, which provide propulsion by vertical movement. Although whales generally do not possess hind limbs, some whales (such as sperm whales and baleen whales) sometimes have rudimentary hind limbs; some even with feet and digits. Most species of whale bear a fin on their backs known as a dorsal fin.

Beneath the skin lies a layer of fat, called blubber. It serves as an energy reservoir and also as insulation. Whales have a four-chambered heart. The neck vertebrae are fused in most whales, which provides stability during swimming at the expense of flexibility. They have a pelvis bone, which is a vestigial structure. Whales breathe through their blowholes, located on the top of the head so the animal can remain submerged. Baleen whales have two; toothed whales have one. The shapes of whales' spouts when exhaling after a dive, when seen from the right angle, differ between species. Whales have a unique respiratory system that lets them stay underwater for long periods of time without taking in oxygen. Some whales, such as the Sperm Whale, can stay underwater for up to two hours holding a single breath. The Blue Whale is the largest known mammal that has ever lived, and the largest living animal, at up to 35 m (105ft) long and 150 tons. Whales generally live for 40–90 years, depending on their species, and on rare occasions can be found to live over a century. Recently a fragment of a lance used by commercial whalers in the 19th century has been found in a bowhead whale caught off Alaska, which showed the whale to be between 115 and 130 years old. Furthermore, a technique for dating age from aspartic acid racemization in the whale eye, combined with a harpoon fragment, indicates an age of 211 years for one male, making bowhead whales the longest lived extant mammal species. Whale flukes often can be used as identifying markings, as is the case for humpback whales. This is the method by which the publicized errant Humphrey the whale was identified in three separate sightings.

A toothed whale, like the sperm whale, possess teeth with cementum cells overlying dentine cells. Unlike human teeth which are comprised mostly of enamel on the tooth portion outside of the gum, whale teeth have cementum outside the gum. Only in larger whales does some enamel show where the cementum has been worn away on the tip of the tooth revealing the underlying enamel.

Whales' ears have specific adaptations to their underwater environment. In humans, the middle ear works as an impedance matcher between the outside air’s low impedance and the cochlear fluid’s high impedance. In aquatic mammals such as whales, however, there is no great difference between the outer and inner environments. Instead of sound passing through outer ear to middle ear, whales receive sound through their lower jaw, where it passes through a low-impedance, fat-filled cavity.

Whales are widely classed as predators, but their food ranges from microscopic plankton to very large fish. Males are called bulls; females, cows. The young are called calves.

As mammals, whales breathe air and must surface to get oxygen. This is done through a blowhole. Many whales also exhibit other surfacing behaviours such as breaching and tail slapping.

Because of their environment (and unlike many animals), whales are conscious breathers: they decide when to breathe. All mammals sleep, including whales, but they cannot afford to fall into an unconscious state for too long, since they need to be conscious to breathe. It is thought that only one hemisphere of their brains sleeps at a time, so that whales are never completely asleep, but still get the rest they need. This is thought because whales often sleep with only one eye closed.

Whales communicate with each other using lyrical sounds, called whale song. Being so large and powerful, these sounds are also extremely loud (depending on the species); sperm whales have only been heard making clicks, as all toothed whales (Odontoceti) use echolocation and can be heard for many miles. They have been known to generate about 20,000 acoustic watts of sound at 163 decibels.

Females give birth to a single calf. Nursing time is long (more than one year in many species), which is associated with a strong bond between mother and young. In most whales reproductive maturity occurs late, typically at seven to ten years. This mode of reproduction spawns few offspring, but provides each with a high probability of survival in the wild.

The male genitals are retracted into cavities of the body during swimming, so as to be streamlined and reduce drag and to prevent injury. Most whales do not maintain fixed partnerships during mating; in many species the females have several mates each season. At birth newborn are delivered tail-first, minimising the risk of drowning.

Whale cows nurse by actively squirting milk the consistency of toothpaste into the mouths of their young preventing loss to the surrounding aquatic environment.

Some species of large whales are listed by various watchdog groups and governments as endangered due to reduced population resulting from commercial whaling. Large whales have been hunted commercially for whale oil, meat, baleen and ambergris (a perfume ingredient from the intestine of sperm whales) since the 1600s. By the middle of the 20th century, whaling left many populations severely depleted.

The International Whaling Commission introduced a six year moratorium on all commercial whaling in 1986, which has been extended to the present day. The moratorium is not absolute, however, and some whaling continues to be practiced under the auspice of research or aboriginal rights; current whaling nations are Norway, Iceland and Japan and the aboriginal communities of Siberia, Alaska and northern Canada.

Several species of small whales are caught as bycatch in fisheries for other species. In the tuna fishery in the Eastern Tropical Pacific thousands of dolphins were drowned in purse-seine nets, until measures to prevent this were introduced. Fishing gear and deployment modifications, and eco-labelling (dolphin-safe or dolphin-friendly brands of canned tuna), have contributed to a reduction in the mortality of dolphins by tuna fishing vessels in recent years. In many countries, small whales are still hunted for food, oil, meat or bait.

Beaver

2009-07-15T13:44:00.000-07:00

Beavers are known for their natural trait of building dams in rivers and streams, and building their homes (known as "lodges") in the resulting pond. Beavers also build canals to float build materials that are difficult to haul over land. They use powerful front teeth to cut trees and plants that they use for building and for food. In the absence of an existing pond a Beaver has to construct a dam before building his lodge. First they place vertical poles and then fill between the vertical poles with a crisscross of horizontally placed branches. They fill in the gaps between the branches with a combination of weeds and mud until the dam holds back sufficient water to surround the lodge.

They are known for their "danger signal": when startled or frightened, a swimming beaver will rapidly dive while forcefully slapping the water with its broad tail. This creates a loud "slap," audible over great distances above and below water. This noise serves as a warning to beavers in the area. Once a beaver has made this danger signal, nearby beavers dive and may not reemerge for some time. Beavers are slow on land, but good swimmers that can stay under water for as long as 15 minutes. Rarely does a frightened beaver attack a human.

Beavers do not hibernate, but store sticks and logs in a pile in their pond. Some of the pile is generally above water which accumulates snow in the winter. The insulation of the snow often keeps the water from freezing in and around their food pile which provides a location where beavers can breathe when outside their lodge.

Fossil remains of beavers are found in the peat and other superficial deposits of Britain and the continent of Europe; while in the Pleistocene formations of Britain and Siberia, occur remains of a giant extinct beaver, Trogontherium cuvieri, representing a genus by itself.

Beavers have webbed hind-feet, and a broad, scaly tail. They have poor eyesight, but keen senses of hearing, smell, and touch.

Beavers continue to grow throughout life. Adult specimens weighing over 25 kg (55 lb) are not uncommon. Females are as large as or larger than males of the same age, which is uncommon among mammals.

The American Beaver (Castor canadensis), also called the Canadian Beaver (which is also the name of a subspecies), or simply Beaver in North America, is native to Canada, much of the United States and parts of northern Mexico. The chief feature distinguishing C. canadensis from C. fiber is the form of the nasal bones of the skull. This species was introduced to the Argentine and Chilean Tierra del Fuego, as well as Finland, France, Poland and Russia.

The American beaver's preferred food is the water-lily (Nuphar luteum), which bears a resemblance to a cabbage-stalk, and grows at the bottom of lakes and rivers. Beavers also gnaw the bark of birch, poplar, and willow trees; but during the summer a more varied herbage, with the addition of berries, is consumed. These animals are often trapped for their fur.

During the early 19th century, trapping eliminated this animal from large portions of its original range. However, through trap and transfer and habitat conservation it made a nearly complete recovery by the 1940s. Beaver reintroduction in British Columbia was facilitated by Eric Collier as recounted in his book Three Against the Wilderness. Beaver furs were used to make clothing and top-hats. Much of the early exploration of North America was driven by the quest for this animal's fur. Native peoples and early settlers also ate this animal's meat. The current beaver population has been estimated to be 10 to 15 million; one estimate claims that there may at one time have been as many as 90 million.

The North American Giant beaver (Castoroides ohioensis) was one of the largest rodents that ever evolved. With a length up to 2.5 m (8.2 ft) it was about the size of a small American Black Bear. It disappeared along with other large mammals in the Holocene extinction event, which began about 13,000 years ago.

The habitat of the beaver is the riparian zone, inclusive of stream bed. The actions of beavers for hundreds of thousands of years in the Northern Hemisphere have kept these watery systems healthy and in good repair, although a human observing all the downed trees might think that the beavers were doing just the opposite.

The beaver works as a keystone species in an ecosystem by creating wetlands that are used by many other species. Next to humans, no other extant animal appears to do more to shape its landscape.

Beavers fell trees for several reasons. They can fell large mature trees, usually in strategic locations, to form the basis of a dam, but European beavers tend to use small diameter (10cm).

Beaver dams are created as a protection against predators, such as coyotes, wolves and bears, and to provide easy access to food during winter. Beavers always work at night and are prolific builders, carrying mud and stones with their fore-paws and timber between their teeth. Because of this, destroying a beaver dam without removing the beavers is difficult, especially if the dam is downstream of an active lodge. Beavers can rebuild such primary dams overnight, though they may not defend secondary dams as vigorously. (Beavers may create a series of dams along a river.)

The ponds created by well-maintained dams help isolate the beavers' home, their lodge, which is also created from severed branches and mud. The beavers cover their lodges late every autumn with fresh mud which freezes when the frost sets in. The mud becomes almost as hard as stone, so that neither wolves nor wolverines can get in.

The lodge has underwater entrances to make entry nearly impossible for any other animal (however, muskrats have been seen living inside beaver lodges with the beavers who made it). A very small amount of the lodge is actually used as a living area. Contrary to popular belief, beavers actually dig out their den with an underwater entrance after they finish building the dam and lodge structure. There are typically two dens within the lodge, one for drying off after exiting the water, and another, drier one where the family actually lives.

Their houses are formed of the same materials as the dams, with little order or regularity of structure, and seldom contain more than four old, and six or eight young beavers. Sometimes some of the larger houses have one or more partitions, but these are only posts of the main building left by the builders to support the roof, for the apartments have usually no communication with each other except by water.

When the ice breaks up in spring they always leave their embankments, and rove about until a little before fall, when they return to their old habitations, and lay in their winter stock of wood. They seldom begin to repair the houses till the frost sets in, and never finish the outer coating till the cold becomes severe. When they erect a new habitation they fell the wood early in summer, but seldom begin building till towards the end of August.

Beavers can create serious damage when spread outside of their natural environment, and are therefore considered in some places as pests or invasive species. For example, in the 1940s, beavers were brought to the island of Tierra Del Fuego in southern Argentina, for commercial fur production. However, the project failed and the beavers were released into the wild. They quickly spread throughout the island, reaching a number of 100,000 individuals within just 50 years (when released into the wild there were only a few pairs). As the habitat is not adapted to withstand the impact of beavers (e.g. unlike in the Northern Hemisphere trees native to Tierra del Fuego do not coppice) beavers have had a detrimental impact. They are now considered a serious invasive species on the island, due to their massive destruction of forest trees, and efforts are being made for their eradication.

After 200 years, a beaver has returned to New York City, making its home along the Bronx River, having spent time living both at the Bronx Zoo as well as the Botanical Gardens. Beavers were trapped to near extinction, and haven't been seen in New York city since the early 1800's. The return of "Jose", named after representative Jose Serano from the Bronx, is seen as evidence that efforts to restore the river have been successful.

In Chicago, several beavers have returned and made a home near the Lincoln Park Zoo. The "Lincoln Park Beaver" has not been as well received by the Chicago Park District, which has killed one beaver and removed several others using live traps, due to concerns over damage to trees in the area.

The importance of the Beaver in the development of Canada through the fur trade led to its designation as the national animal. It is depicted on the Canadian five-cent piece and was on the first pictorial postage stamp issued in the Canadian colonies in 1849 (the so-called "Three-Penny Beaver"). As a national symbol, the beaver was chosen to be the mascot of the 1976 Summer Olympics held in Montreal with the name "Amik" ("beaver" in Ojibwe). The beaver is also the symbol of many units and organizations within the Canadian Forces, such as on the cap badges of the Royal 22e Régiment and the Canadian Military Engineers. Toronto Police Services, London Police Service, Canadian Pacific Railway Police Service and Canadian Pacific Railway crest bears the beaver on their crest or coat of arms.

In the 17th century, based on a question raised by the Bishop of Quebec, the Roman Catholic Church ruled that the beaver was a fish (beaver flesh was a part of the indigenous peoples' diet, prior to the Europeans' arrival) for purposes of dietary law. Therefore, the general prohibition on the consumption of meat on Fridays during Lent does not apply to beaver meat. The legal basis for the decision probably rests with the Summa Theologica of Thomas Aquinas, which bases animal classification as much on habit as anatomy.

Olingo

2009-07-13T14:08:00.000-07:00

Olingos are small procyonids that comprise the genus Bassaricyon, native to the rainforests of Central and South America from Nicaragua to Peru. They are arboreal and nocturnal, and live at elevations from sea level to 2,000 m. Olingos closely resemble the kinkajou in morphology and habits, though they lack prehensile tails and extrudable tongues, have more extended muzzles, and possess an anal scent gland. Genetic studies have shown that the closest relatives of the olingos are actually the coatis. The similarities between kinkajous and olingos are thus an example of parallel evolution.

The status of the various olingos is disputed: only the Bushy-tailed Olingo (Bassaricyon gabbii) is particularly well-known, and it is usually confusingly referred to simply as an olingo. The other species of olingos may prove to be only subspecies of it. Olingos are quite rare in zoos and are often misidentified as kinkajous. An undescribed olingo closely related to Bassaricyon alleni was discovered in 2006 by Kristofer Helgen at Las Maquinas in the Andes of Ecuador.

Olingos are found in the rainforest of Columbia, Costa Rico, Ecuador, Honduras, Nicaragua, Panama, Peru and Venezuela.

The Olingo has short fur that is light brown with cream on the undersides and neck of the animal. They are 35 to 48 cm (14 to 19 in ) long, not including their tails, which can measure up to 48 cm (19 in). They weigh 10 to 15 kg (22 to 33 Ib). The tails of olingos are not prehensile and are decorated with dark rings that do not close on the underside of the tail. Because of the color of its fur and the similar build olingos are often confused with kinkajous. The olingos characteristic features are a round head, which is flattened on top, the small round ears, and a pointed muzzle with a dark gray nose. The eyes have large pupils and the iris is a cinnamon color, the eyes contract horizontally. They have 40 sharp teeth in a structure of molars, premolars and canines. They also have sharp curved claws.

Lion

2009-07-13T11:19:00.000-07:00

The lion (Panthera leo) is one of four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg (550 lb) in weight, it is the second-largest living cat after the tiger. Wild lions currently exist in Sub-Saharan Africa and in Asia with a critically endangered remnant population in northwest India, having disappeared from North Africa, the Middle East, and Western Asia in historic times. Until the late Pleistocene, which was about 10,000 years ago, the lion was the most widespread large land mammal after humans. They were found in most of Africa, much of Eurasia from western Europe to India, and in the Americas from the Yukon to Peru.

Lions live for around 10–14 years in the wild, while in captivity they can live over 20 years. In the wild, males seldom live longer than ten years as fights with rivals occasionally cause injuries. They typically inhabit savanna and grassland, although they may take to bush and forest. Lions are unusually social compared to other cats. A pride of lions consists of related females and offspring and a small number of adult males. Groups of female lions typically hunt together, preying mostly on large ungulates. The lion is an apex and keystone predator, although they will scavenge if the opportunity arises. While lions do not typically hunt humans selectively, some have been known to become man-eaters and seek human prey.

The lion is a vulnerable species, having seen a possibly irreversible population decline of 30 to 50 percent over the past two decades in its African range. Lion populations are untenable outside of designated reserves and national parks. Although the cause of the decline is not fully understood, habitat loss and conflicts with humans are currently the greatest causes of concern. Lions have been kept in menageries since Roman times and have been a key species sought for exhibition in zoos the world over since the late eighteenth century. Zoos are cooperating worldwide in breeding programs for the endangered Asiatic subspecies.

Visually, the male lion is highly distinctive and is easily recognized by its mane. The lion, particularly the face of the male, is one of the most widely recognized animal symbols in human culture. Depictions have existed from the Upper Paleolithic period, with carvings and paintings from the Lascaux and Chauvet Caves, through virtually all ancient and medieval cultures where they historically occurred. It has been extensively depicted in literature, in sculptures, in paintings, on national flags, and in contemporary films and literature.

The oldest lion-like fossil is known from Laetoli in Tanzania and is perhaps 3.5 million years old; some scientists have identified the material as Panthera leo. These records are not well-substantiated, and all that can be said is that they pertain to a Panthera-like felid. The oldest confirmed records of Panthera leo in Africa are about 2 million years younger. The closest relatives of the lion are the other Panthera species: the tiger, the jaguar, and the leopard. Morphological and genetic studies reveal that the tiger was the first of these recent species to diverge. About 1.9 million years ago the jaguar branched off the remaining group, which contained ancestors of the leopard and lion. The lion and leopard subsequently separated about 1 to 1.25 million years ago from each other.

Panthera leo itself evolved in Africa between 1 million and 800,000 years ago, before spreading throughout the Holarctic region. It appeared in Europe for the first time 700,000 years ago with the subspecies Panthera leo fossilis at Isernia in Italy. From this lion derived the later Cave Lion (Panthera leo spelaea), which appeared about 300,000 years ago. During the upper Pleistocene the lion spread to North and South America, and developed into Panthera leo atrox, the American Lion. Lions died out in northern Eurasia and America at the end of the last glaciation, about 10,000 years ago; this may have been secondary to the extinction of Pleistocene megafauna.

Traditionally, twelve recent subspecies of lion were recognized, the largest of which has been recognized as the Barbary Lion. The major differences separating these subspecies are location, mane appearance, size, and distribution. Because these characteristics are very insignificant and show a high individual variability, most of these forms were debatable and probably invalid; additionally, they often were based upon zoo material of unknown origin that may have had "striking, but abnormal" morphological characteristics. Today only eight subspecies usually are accepted, but one of these (the Cape Lion formerly described as Panthera leo melanochaita) probably is invalid. Even the remaining seven subspecies might be too many; mitochondrial variation in recent African lions is modest, which suggests that all sub-Saharan lions could be considered a single subspecies, possibly divided in two main clades: one to the west of the Great Rift Valley and the other to the east. Lions from Tsavo in Eastern Kenya are much closer genetically to lions in Transvaal (South Africa), than to those in the Aberdare Range in Western Kenya.

Lions have been known to breed with tigers (most often the Siberian and Bengal subspecies) to create hybrids called ligers and tigons. They also have been crossed with leopards to produce leopons, and jaguars to produce jaglions. The marozi is reputedly a spotted lion or a naturally occurring leopon, while the Congolese Spotted Lion is a complex lion-jaguar-leopard hybrid called a lijagulep. Such hybrids once commonly were bred in zoos, but this is now discouraged due to the emphasis on conserving species and subspecies. Hybrids are still bred in private menageries and in zoos in China.

The liger is a cross between a male lion and a tigress. Because the growth-inhibiting gene from the female tiger is absent, a growth-promoting gene is passed on by the male lion, the resulting ligers grow far larger than either parent. They share physical and behavioural qualities of both parent species (spots and stripes on a sandy background). Male ligers are sterile, but female ligers are often fertile. Males have about a 50 percent chance of having a mane, but if they grow one, their manes will be modest: around 50 percent of a pure lion mane. Ligers are typically between 3.0 and 3.7 m (10 to 12 feet) in length, and can be between 360 and 450 kg (800 to 1,000 pounds) or more. The less common tigon is a cross between the lioness and the male tiger.

The lion is the tallest (at the shoulder) of the felines, and also is the second-heaviest feline after the tiger. With powerful legs, a strong jaw, and 8 cm (3.1 in) long canine teeth, the lion can bring down and kill large prey. The skull of the lion is very similar to that of the tiger, though the frontal region is usually more depressed and flattened, with a slightly shorter postorbital region. The lion's skull has broader nasal openings than the tiger. However, due to the amount of skull variation in the two species, usually, only the structure of the lower jaw can be used as a reliable indicator of species. Lion coloration varies from light buff to yellowish, reddish, or dark ochraceous brown. The underparts are generally lighter and the tail tuft is black. Lion cubs are born with brown rosettes (spots) on their body, rather like those of a leopard. Although these fade as lions reach adulthood, faint spots often may still be seen on the legs and underparts, particularly on lionesses.

Lions are the only members of the cat family to display obvious sexual dimorphism—that is, males and females look distinctly different. They also have specialized roles that each gender plays in the pride. For instance, the lioness, the hunter, lacks the male's thick cumbersome mane. It seems to impede the male's ability to be camouflaged when stalking the prey and create overheating in chases. The color of the male's mane varies from blond to black, generally becoming darker as the lion grows older.

Weights for adult lions generally lie between 150–250 kg (330–550 lb) for males and 120–182 kg (264–400 lb) for females. Nowell and Jackson report average weights of 181 kg for males and 126 kg for females; one male shot near Mount Kenya was weighed at 272 kg (600 lb). Lions tend to vary in size depending on their environment and area, resulting in a wide spread in recorded weights. For instance, lions in southern Africa tend to be about 5 percent heavier than those in East Africa, in general.

Head and body length is 170–250 cm (5 ft 7 in – 8 ft 2 in) in males and 140–175 cm (4 ft 7 in – 5 ft 9 in) in females; shoulder height is about 123 cm (4 ft) in males and 107 cm (3 ft 6 in) in females. The tail length is 90-105 cm (2 ft 11 in - 3 ft 5 in) in males and 70–100 cm in females (2 ft 4 in – 3 ft 3 in). The longest known lion was a black-maned male shot near Mucsso, southern Angola in October 1973; the heaviest known lion was a man-eater shot in 1936 just outside Hectorspruit in eastern Transvaal, South Africa and weighed 313 kg (690 lb). Lions in captivity tend to be larger than lions in the wild—the heaviest lion on record is a male at Colchester Zoo in England named Simba in 1970, who weighed 375 kg (826 lb).

The most distinctive characteristic shared by both females and males is that the tail ends in a hairy tuft. In some lions, the tuft conceals a hard "spine" or "spur", approximately 5 mm long, formed of the final sections of tail bone fused together. The lion is the only felid to have a tufted tail—the function of the tuft and spine are unknown. Absent at birth, the tuft develops around 5½ months of age and is readily identifiable at 7 months. The mane of the adult male lion, unique among cats, is one of the most distinctive characteristics of the species.

It makes the lion appear larger, providing an excellent intimidation display; this aids the lion during confrontations with other lions and with the species' chief competitor in Africa, the spotted hyena. The presence, absence, color, and size of the mane is associated with genetic precondition, sexual maturity, climate, and testosterone production; the rule of thumb is the darker and fuller the mane, the healthier the lion. Sexual selection of mates by lionesses favors males with the densest, darkest mane. Research in Tanzania also suggests mane length signals fighting success in male-male relationships. Darker-maned individuals may have longer reproductive lives and higher offspring survival, although they suffer in the hottest months of the year. In prides including a coalition of two or three males, it is possible that lionesses solicit mating more actively with the males who are more heavily maned.

Scientists once believed that the distinct status of some subspecies could be justified by morphology, including the size of the mane. Morphology was used to identify subspecies such as the Barbary Lion and Cape Lion. Research has suggested, however, that environmental factors influence the color and size of a lion's mane, such as the ambient temperature. The cooler ambient temperature in European and North American zoos, for example, may result in a heavier mane. Thus the mane is not an appropriate marker for identifying subspecies. The males of the Asiatic subspecies, however, are characterized by sparser manes than average African lions.

Maneless male lions have been reported in Senegal and Tsavo East National Park in Kenya, and the original male white lion from Timbavati also was maneless. Castrated lions have minimal manes. The lack of a mane sometimes is found in inbred lion populations; inbreeding also results in poor fertility.

Many lionesses have a ruff that may be apparent in certain poses. Sometimes it is indicated in sculptures and drawings, especially ancient artwork, and is misinterpreted as a male mane. It differs from a mane, however, in being at the jaw line below the ears, of much less hair length, and frequently not noticeable, whereas a mane extends above the ears of males, often obscuring their outline entirely.

Cave paintings of extinct European Cave Lions exclusively show animals with no mane, or just the hint of a mane, suggesting to some that they were more or less maneless; however, females hunting for a pride are the likely subjects of the drawings—since they are shown in a group related to hunting—so these images do not enable a reliable judgment about whether the males had manes. The drawings do suggest that the extinct species used the same social organization and hunting strategies as contemporary lions.

The white lion is not a distinct subspecies, but a special morph with a genetic condition, leucism, that causes paler colouration akin to that of the white tiger; the condition is similar to melanism, which causes black panthers. They are not albinos, having normal pigmentation in the eyes and skin. White Transvaal lion (Panthera leo krugeri) individuals occasionally have been encountered in and around Kruger National Park and the adjacent Timbavati Private Game Reserve in eastern South Africa, but are more commonly found in captivity, where breeders deliberately select them. The unusual cream color of their coats is due to a recessive gene. Reportedly, they have been bred in camps in South Africa for use as trophies to be killed during canned hunts.

Confirmation of the existence of white lions only came in the late twentieth century. For hundreds of years prior, the white lion had been thought to be a figment of legend circulating in South Africa, the white pelage of the animal said to represent the goodness in all creatures. Sightings were first reported in the early 1900s, and continued, infrequently, for almost fifty years until, in 1975, a litter of white lion cubs was found at Timbavati Game Reserve.

Though adult lions have no natural predators, evidence suggests that the majority die violently from humans or other lions. This is particularly true of male lions, who, as the main defenders of the pride, are more likely to come into aggressive contact with rival males. In fact, even though a male lion may reach an age of 15 or 16 years if he manages to avoid being ousted by other males, the majority of adult males do not live to be more than 10 years old. This is why the average lifespan of a male lion tends to be significantly less than that of a lioness in the wild. However, members of both sexes can be injured or even killed by other lions when two prides with overlapping territories come into conflict.

Lions have an array of facial expressions and body postures that serve as visual gestures. Their repertoire of vocalizations is also large; variations in intensity and pitch, rather than discrete signals, appear central to communication. Lion sounds include snarling, purring, hissing, coughing, miaowing, woofing and roaring. Lions tend to roar in a very characteristic manner, starting with a few deep, long roars that trail off into a series of shorter ones. They most often roar at night; the sound, which can be heard from a distance of 8 kilometres (5.0 mi), is used to advertise the animal's presence. Lions have the loudest roar of any big cat.

The relationship between lions and spotted hyenas in areas where they coexist is unique in its complexity and intensity. Lions and spotted hyenas are both apex predators which feed on the same prey, and are therefore in direct competition with one another. As such, they will often fight over and steal each others' kills. Though hyenas are popularly assumed to be opportunistic scavengers profiting from the lion's hunting abilities, it is quite often the case that the reverse is true. In Tanzania's Ngorongoro Crater, the spotted hyena population greatly exceeds that of the resident lions, which obtain a large proportion of their food by stealing hyena prey. The feud between the two species, however, extends beyond battles over food. In animals, it is usually the case that territorial boundaries of another species are disregarded. Hyenas and lions are an exception to this; they set boundaries against each other as they would against members of their own species. Male lions in particular are extremely aggressive toward hyenas, and have been observed to hunt and kill hyenas without eating them. Conversely, hyenas are major predators of lion cubs, and will harass lionesses over kills. However, healthy adult males, even single ones, are generally avoided at all costs.

Lions tend to dominate smaller felines such as cheetahs and leopards in areas where they are sympatric. They will steal their kills and will kill their cubs and even adults when given the chance. The cheetah has a 50 percent chance of losing its kill to lions or other predators. Lions are major killers of cheetah cubs, up to 90 percent of which are lost in their first weeks of life due to attacks by other predators. Cheetahs avoid competition by hunting at different times of the day and hide their cubs in thick brush. Leopards also use such tactics, but have the advantage of being able to subsist much better on small prey than either lions or cheetahs.

Also, unlike cheetahs, leopards can climb trees and use them to keep their cubs and kills away from lions. However, lionesses will occasionally be successful in climbing to retrieve leopard kills. Similarly, lions dominate African wild dogs, not only taking their kills but also preying on both young and adult dogs (although the latter are rarely caught).

The Nile crocodile is the only sympatric predator (besides humans) that can singly threaten the lion. Depending on the size of the crocodile and the lion, either can lose kills or carrion to the other. Lions have been known to kill crocodiles venturing onto land, while the reverse is true for lions entering waterways containing crocodiles, as evidenced by the fact that lion claws have on occasion been found in crocodile stomachs.

Most lions now live in eastern and southern Africa, and their numbers there are rapidly decreasing, with an estimated 30–50 percent decline over the last two decades. Currently, estimates of the African lion population range between 16,500 and 47,000 living in the wild in 2002–2004, down from early 1990s estimates that ranged as high as 100,000 and perhaps 400,000 in 1950. The cause of the decline is not well-understood, and may not be reversible. Currently, habitat loss and conflicts with humans are considered the most significant threats to the species. The remaining populations are often geographically isolated from each other, which can lead to inbreeding, and consequently, a lack of genetic diversity. Therefore the lion is considered a vulnerable species by the International Union for Conservation of Nature and Natural Resources, while the Asiatic subspecies is critically endangered. The lion population in the region of West Africa is isolated from lion populations of Central Africa, with little or no exchange of breeding individuals. The number of mature individuals in West Africa is estimated by two separate recent surveys at 850–1,160 (2002/2004). There is disagreement over the size of the largest individual population in West Africa: the estimates range from 100 to 400 lions in Burkina Faso's Arly-Singou ecosystem.

Conservation of both African and Asian lions has required the setup and maintenance of national parks and game reserves; among the best known are Etosha National Park in Namibia, Serengeti National Park in Tanzania, and Kruger National Park in eastern South Africa. Outside these areas, the issues arising from lions' interaction with livestock and people usually results in the elimination of the former. In India, the last refuge of the Asiatic lion is the 1,412 km² (558 square miles) Gir Forest National Park in western India which had about 359 lions (as of April 2006). As in Africa, numerous human habitations are close by with the resultant problems between lions, livestock, locals and wildlife officials. The Asiatic Lion Reintroduction Project plans to establish a second independent population of Asiatic Lions at the Kuno Wildlife Sanctuary in the Indian state of Madhya Pradesh. It is important to start a second population to serve as a gene pool for the last surviving Asiatic lions and to help develop and maintain genetic diversity enabling the species to survive.

The former popularity of the Barbary lion as a zoo animal has meant that scattered lions in captivity are likely to be descended from Barbary Lion stock. This includes twelve lions at Port Lympne Wild Animal Park in Kent, England that are descended from animals owned by the King of Morocco. Another eleven animals believed to be Barbary lions were found in Addis Ababa zoo, descendants of animals owned by Emperor Haile Selassie. WildLink International, in collaboration with Oxford University, launched their ambitious International Barbary Lion Project with the aim of identifying and breeding Barbary lions in captivity for eventual reintroduction into a national park in the Atlas Mountains of Morocco.

Following the discovery of the decline of lion population in Africa, several coordinated efforts involving lion conservation have been organised in an attempt to stem this decline. Lions are one species included in the Species Survival Plan, a coordinated attempt by the Association of Zoos and Aquariums to increase its chances of survival. The plan was originally started in 1982 for the Asiatic lion, but was suspended when it was found that most Asiatic lions in North American zoos were not genetically pure, having been hybridized with African lions. The African lion plan started in 1993, focusing especially on the South African subspecies, although there are difficulties in assessing the genetic diversity of captive lions, since most individuals are of unknown origin, making maintenance of genetic diversity a problem.

Widely seen in captivity, lions are part of a group of exotic animals that are the core of zoo exhibits since the late eighteenth century; members of this group are invariably large vertebrates and include elephants, rhinoceroses, hippopotamuses, large primates, and other big cats; zoos sought to gather as many of these species as possible. Though many modern zoos are more selective about their exhibits, there are over 1000 African and 100 Asiatic lions in zoos and wildlife parks around the world. They are considered an ambassador species and are kept for tourism, education and conservation purposes. Lions can reach an age of over 20 years in captivity; Apollo, a resident lion of Honolulu Zoo in Honolulu, Hawaii, died at age 22 in August 2007. His two sisters, born in 1986, are still living. A zoo-based lion breeding programme usually takes into account the separation of the various lion subspecies, while mitigating the inbreeding that is likely to occur when animals are divided by subspecies.

Llama

2009-07-11T12:59:00.000-07:00

The llama (Lama glama) is a South American camelid, widely used as a pack animal by the Incas and other natives of the Andes mountains. In South America llamas are still used as beasts of burden, as well as for the production of fiber and meat.

The height of a full-grown, full-size llama is between 5.5 ft (1.7 m) to 6 ft (1.8 m) tall at the top of the head. They can weigh between approximately 280 lb (130 kg) and 450 lb (200 kg). At birth, a baby llama (called a cria) can weigh between 20 lb (9.1 kg) to 30 lb (14 kg). Llamas are very social animals and like to live with other llamas as a herd. Overall, the fiber produced by a llama is very soft and is naturally lanolin free. Llamas are intelligent and can learn simple tasks after a few repetitions. When using a pack, llamas can carry about 25% to 30% of their body weight for several miles.

Llamas appear to have originated from the central plains of North America about 40 million years ago. They migrated to South America and Asia about 3 million years ago. By the end of the last ice age (10,000–12,000 years ago) camelids were extinct in North America. As of 2007, there were over 7 million llamas and alpacas in South America and, due to importation from South America in the late 20th century, there are now over 100,000 llamas and 6,500–7,000 alpacas in the US and Canada.

Although early writers compared llamas to sheep, their similarity to the camel was soon recognized. They were included in the genus Camelus along with alpaca in the Systema Naturae (1758) of Linnaeus. They were, however, separated by Cuvier in 1800 under the name of llama along with the guanaco. Alpacas and vicuñas are in genus Vicugna. The genera Lama and Vicugna are, with the two species of true camels, the sole existing representatives of a very distinct section of the Artiodactyla or even-toed ungulates, called Tylopoda, or "bump-footed," from the peculiar bumps on the soles of their feet. The Tylopoda consists of a single family, the Camelidae, and shares the order Artiodactyla with the Suina (pigs), the Tragulina (chevrotains), the Pecora (ruminants), and the Cetancodonta (hippos and cetaceans, which belong to Artiodactyla from a cladistic if not traditional standpoint). The Tylopoda have more or less affinity to each of the sister taxa, standing in some respects in a middle position between them, sharing some characteristics from each, but in others showing special modifications not found in any of the other taxa.

The 19th century discoveries of a vast and previously unexpected extinct Tertiary fauna of North America, as interpreted by palaeontologists Leidy, Cope, and Marsh, aided understanding of the early history of this family.

Llamas were not always confined to South America; abundant llama-like remains were found in Pleistocene deposits in the Rocky Mountains and in Central America. Some of the fossil llamas were much larger than current forms. Some species remained in North America during the last ice ages. North American llamas are categorized as a single extinct genus, Hemiauchenia. Llama-like animals would have been a common sight in 25,000 years ago, in modern-day California, Texas, New Mexico, Utah, Missouri, and Florida.

The camelid lineage has a good fossil record. Camel-like animals have been traced from the thoroughly differentiated modern species back through early Miocene forms. Their characteristics became more general, and they lost those that distinguished them as camelids; hence they were classified as ancestral artiodactyls. No fossils of these earlier forms have been found in the Old World, indicating that North America was the original home of camelids, and that Old World camels crossed over via the Bering land bridge. The formation of the Isthmus of Panama three million years ago allowed camelids to spread to South America as part of the Great American Interchange, where they evolved further. Meanwhile, North American camelids died out at the end of the Pleistocene.

The llama and alpaca are only known in the domestic state, and are variable in size and of many colors, being often white, brown, or piebald. Some are grey or black. The guanaco and vicuña are wild, the former being endangered, and of a nearly uniform light-brown color, passing into white below. They certainly differ from each other, the vicuña being smaller, more slender in its proportions, and having a shorter head than the guanaco. The vicuña lives in herds on the bleak and elevated parts of the mountain range bordering the region of perpetual snow, amidst rocks and precipices, occurring in various suitable localities throughout Peru, in the southern part of Ecuador, and as far south as the middle of Bolivia. Its manners very much resemble those of the chamois of the European Alps; it is as vigilant, wild, and timid. The fiber is extremely delicate and soft, and highly valued for the purposes of weaving, but the quantity which each animal produces is minimal. Alpaca are descended from a wild vicuna ancestor while the domesticated llama is descended from a wild guanaco ancestor, though at this point there has been a considerable amount of hybridization between the two species.

Differentiating characteristics between llamas and alpacas include the llama's larger size and longer head. Alpaca fiber is generally more expensive but not always more valuable. Alpacas tend to have a more consistent color throughout the body. The most apparent visual difference between llamas and camels is that camels have a hump or humps and llamas do not.

Commonly unknown, llamas do not have eyelashes. However, their cousin the alpaca does.

Llamas which are well-socialized and trained to halter and lead after weaning are very friendly and pleasant to be around. They are extremely curious and most will approach people easily. However, llamas that are bottle-fed or over-socialised and over-handled as youngsters will become extremely difficult to handle when mature, when they will begin to treat humans as they treat each other, which is characterized by bouts of spitting, kicking and neck wrestling. Anyone having to bottle-feed a cria should keep contact to a minimum and stop as soon as possible.

When correctly reared spitting at a human is a rare thing. Llamas are very social herd animals, however, and do sometimes spit at each other as a way of disciplining lower-ranked llamas in the herd. A llama's social rank in a herd is never static. They can always move up or down in the social ladder by picking small fights. This is usually done between males to see who becomes alpha. Their fights are visually dramatic with spitting, ramming each other with their chests, neck wrestling and kicking, mainly to knock the other off balance. The females are usually only seen spitting as a means of controlling other herd members.

While the social structure might always be changing, they live as a family and they do take care of each other. If one notices a strange noise or feels threatened, a warning bray is sent out and all others come to alert. They will often hum to each other as a form of communication.

The sound of the llama making groaning noises or going "mwa" is often a sign of fear or anger. If a llama is agitated, it will lay its ears back. One may determine how agitated the llama is by the materials in the spit. The more irritated the llama is, the further back into each of the three stomach compartments it will try to draw materials from for its spit.

An "orgle" is the mating sound of a llama or alpaca, made by the sexually aroused male. The sound is reminiscent of gargling, but with a more forceful, buzzing edge. Males begin the sound when they become aroused and continue throughout the act of procreation—from 15 minutes to more than an hour.

Using llamas as livestock guards in North America began in the early 1980s and some sheep producers have used llamas successfully for that entire time. The use of guard llamas has greatly increased since a magazine article in 1990, when national attention was drawn to the potential use of llamas for guarding sheep. The ideal guard animal should protect sheep against predation while requiring minimal training, care, and maintenance. It should stay with and not disrupt the flock, and live long enough to be cost effective. A variety of guard animals currently in use include dogs, donkeys, kangaroos, ostriches, and llamas. Of these, guard dogs are still the most common; guard llamas number only in the hundreds. Studies have proven that llamas are successfully being used as guard animals for herds of sheep, goats, alpacas and other livestock throughout the North America. Protection of the herd and easy maintenance are the two most commonly cited advantages. Llamas are introduced to a herd and are pastured with them; they do not require separate shelters. Ideally, a llama should be introduced to the sheep while they are in a corral or small pasture rather than on open range or large pasture. The llama should remain in a small area until the sheep and llama seem well-adjusted and attached to each other. This encourages bonding between the sheep and llama. A llama introduced in this manner will be more effective as a guard against predators.

Research supports the use of multiple guard llamas is not as effective as one llama. Multiple male llamas tend to bond with one another, rather than with the livestock, and may ignore the flock. A gelded male of two years of age bonds closely with its new charges and is instinctively very effective in preventing predation. Some llamas appear to bond more quickly to sheep or goats if they are introduced just prior to lambing. Many sheep and goat producers indicate a special bond quickly develops between lambs and their guard llama and that the llama is particularly protective of the lambs.

Using llamas as guards has eliminated the losses to predators for many producers. The value of the livestock saved each year more than exceeds the purchase cost and annual maintenance of a llama. Although not every llama is suited to the job, most llamas are a viable, non-lethal alternative for reducing predation, requiring no training and little care.

One of the main uses for llamas at the time of the Spanish conquest was to bring down ore from the mines in the mountains. Gregory de Bolivar estimated that in his day, as many as three hundred thousand were employed in the transport of produce from the Potosí mines alone, but since the introduction of horses, mules, and donkeys, the importance of the llama as a beast of burden has greatly diminished.

The Inca deity Urcuchillay was depicted in the form of a multicolored llama. The Moche people frequently placed llamas and llama parts in the burials of important people, as offerings or provisions for the afterlife. The Moche culture of pre-Columbian Peru depicted llamas quite realistically in their ceramics.

Panther

2009-07-09T20:15:00.000-07:00

A black panther is a black (melanistic) colour variant of one of several species of larger cat which are known by the term panther in various parts of the world. "Panther" in North America is most commonly used for the cougar (genus Puma), in Latin America it is most often used to mean a jaguar and elsewhere in the world it usually refers to the leopard (both genus Panthera). The name "panther" is often limited to black panthers, but it is also used to refer to those which are normally-colored for the species (tawny or spotted), or to white panthers.

Melanism is most common in the jaguar (Panthera onca), where it is carried by a dominant allele, and the leopard (Panthera pardus), where it is due to a recessive allele, a pair or series of a gene coding sequences. Close examination of the color of these black cats will show that the typical markings are still there, but are hidden by the excess black pigment melanin, giving an effect similar to that of printed silk. Melanistic and non-melanistic animals can be littermates. In those species that hunt mainly at night, the condition is not detrimental. Albino or leucistic individuals of the same three species are known as white panthers.

It is thought that melanism may confer a selective advantage under certain conditions since it is more common in regions of dense forest, where light levels are lower. Recent, preliminary studies also suggest that melanism might be linked to beneficial mutations in the immune system.

Black leopards are reported from most densely forested areas in southwestern China, Myanmar, Assam and Nepal, from Travancore and other parts of southern India and are said to be common in Java and the southern part of the Malay Peninsula where they may be more numerous than spotted leopards. They are less common in tropical Africa, but have been reported from Ethiopia (formerly Abyssinia), from the forests of Mount Kenya and from the Aberdares. One was recorded by Peter Turnbull-Kemp in the equatorial forest of Cameroon. Skin color is a mixture of blue, black, gray, and purple with rosettes.

Melanistic leopards are the most common form of black panther in captivity and they have been selectively bred for decades in the zoo and exotic pet trades. Black leopards are smaller and more lightly built than normally-pigmented individuals.

It is a myth that black leopards are often rejected by their mothers at an early age because of their color. In actuality, poor temperament has been bred into the captive strains as a side-effect of inbreeding and it is this poor temperament that leads to problems of maternal care in captivity. According to Funk and Wagnalls' Wildlife Encyclopedia, captive black leopards are less fertile than normal leopards, with average litter sizes of 1.8 and 2.1, respectively. This is likely due to inbreeding depression.

In the early 1980s, the Glasgow Zoo, in Scotland, acquired a 10 year old black leopard, nicknamed the Cobweb Panther, from the Dublin Zoo in Ireland. She was exhibited for several years before being moved to the Madrid Zoo, in Spain. This leopard had a uniformly black coat profusely sprinkled with white hairs as though draped with spider webs.

The condition appeared to be vitiligo; as she aged, the white became more extensive. Since then, other "Cobweb Panthers" have been reported and photographed in zoos.

In jaguars, the melanism allele is dominant. Consequently, black jaguars can produce black or spotted cubs, but a pair of spotted jaguars will only produce spotted cubs. This is in contrast to the leopards wherein the mutation is recessive; spotted leopards can produce black cubs if both parents carry the recessive allele. Black leopards always breed true when mated together. The gene is incompletely dominant. Individuals with two copies of the gene are darker (the black background colour is more dense) than individuals with just one copy whose background colour may appear to be dark charcoal rather than black.

A black jaguar, named "Diablo", was inadvertently crossed with a lioness, named "Lola", at the Bear Creek Wildlife Sanctuary in Barrie, Canada. The offspring were a charcoal black jaglion female and a tan-colored, spotted jaglion male. It therefore appears that the jaguar melanism gene is also dominant over normal lion coloration (the black jaguar sire was presumably carrying the black on only one allele). In preserved, stuffed specimens, black leopards often fade to a rusty color but black jaguars fade to chocolate brown.

The Florida panther, Florida’s state animal, is one of the most endangered mammals on earth. It is tawny brown on the back and pale gray underneath. The Florida panther is one of 30 Puma concolor subspecies known by many names – puma, cougar, mountain lion, painter, catamount and panther. Estimated at fewer than 100 adults and subadults in the only known breeding population (South Florida).

Historically ranged across the southeastern United States including Arkansas, Louisiana, Mississippi, Alabama, Georgia, Florida, and parts of Tennessee and South Carolina. Now, the breeding population is found only in the southern tip of Florida, south of the Caloosahatchee River. In recent years, young male panthers have traveled as far as northeast Florida. Females do not roam as widely.

Prairie Dogs

2009-07-08T08:46:00.000-07:00

Prairie dogs (Cynomys) are burrowing rodents (not actually dogs) native to the grasslands of North America. There are five different species of prairie dogs: black-tailed, white-tailed, Gunnison, Utah, and Mexican prairie dogs. They are a type of ground squirrel. On average, these stout-bodied rodents will grow to be between 30–40 centimetres (12–16 in) long, including the short tail and weigh between 0.5–1.5 kilograms (1–3 lb). They are found in the United States, Canada, and Mexico. In Mexico, prairie dogs are primarily found in the northern states which are the southern end of the great plains: northeastern Sonora, north and northeastern Chihuahua, northern Coahuila, northern Nuevo León, and northern Tamaulipas; in the U.S., they range primarily west of the Mississippi River, though they have also been introduced in a few eastern locales. They will eat all sorts of vegetables and fruits.

The highly social prairie dogs live in large colonies or "towns" – collections of prairie dog families that can span hundreds of acres. Families usually consist of 1 male and 2 to 4 females living in a strict social hierarchy. Prairie dog pups reach sexual maturity at about 3 years of age, and after their third winter the dominant male in a given family will drive them away, forcing them to establish their own families on the edges of the colony. The dominant male will defend the family's borders against rival prairie dogs, and disputes are resolved by fighting. Prairie dogs are also aggressive against predators such as badgers and snakes. Prairie dogs are social animals, however, and often make social visits with each other, and greet each other with a sort of kiss.

Prairie dog tunnel systems help channel rainwater into the water table to prevent runoff and erosion, and can also serve to change the composition of the soil in a region by reversing soil compaction that can be a result of cattle grazing. The tunnels usually have several chambers. Tunnels can descend vertically as much as 5 metres (16 ft), and can extend laterally as much as 30 metres (98 ft). Prairie dogs line their burrows with grass to insulate them, and the earth excavated from the burrow is piled up in mounds around the burrow's entrance. The prairie dogs use these carefully maintained mounds as observation posts.

The prairie dog is well adapted to predators. Using its dichromatic color vision, it can detect predators from a far distance and then alert other prairie dogs to the danger with a special, high-pitched call. Con Slobodchikoff and others assert that prairie dogs use a sophisticated system of vocal communication to describe specific predators. Prairie dogs also trim the vegetation around their colonies, perhaps to remove any cover for predators. Their burrows generally contain several routes of escape.

The prairie dog is chiefly herbivorous, though it eats some insects. It feeds primarily on grasses and, in the fall, broadleaf forbs. Prairie dogs have 1-6 pups (babies) yearly, which are born blind and furless and need about 30 days of close nurturing from their mother.

Ecologists consider this rodent to be a keystone species. They are an important prey species, being the primary diet in prairie species such as the Black-footed Ferret, the Swift Fox, the Golden Eagle, the badger, and the Ferruginous Hawk. Other species, such as the Mountain Plover and the Burrowing Owl, also rely on prairie dog burrows for nesting areas. Even grazing species such as bison, pronghorn, and mule deer have shown a proclivity for grazing on the same land used by prairie dogs. It is believed that they prefer the vegetative conditions after prairie dogs have foraged through the area.

Nevertheless, prairie dogs are often identified as pests and exterminated from agricultural properties because they are capable of damaging crops, as they clear the immediate area around their burrows of most vegetation.

As a result, prairie dog habitat has been impacted by direct removal by ranchers and farmers as well as the more obvious encroachment of urban development which has greatly reduced their populations. The removal of prairie dogs "causes undesirable spread of brush" the costs of which to livestock range may outweigh the benefits of removal. The largest remaining community comprises Black-tailed Prairie Dogs. In spite of human encroachment, prairie dogs have adapted, continuing to dig burrows in open areas of western cities.

One common concern which led to the widespread extermination of prairie dog colonies was that their digging activities could injure horses by fracturing their limbs. However, according to writer Fred Durso, Jr. of E Magazine, "after years of asking ranchers this question, we have found not one example." Another concern is their susceptibility to bubonic plague.

Until 2003, primarily black-tailed prairie dogs were collected from the wild for the exotic pet trade in Canada, the United States, Japan, and Europe. They were removed from their underground burrows each spring, as young pups, with a large vacuum device. They are difficult to breed in captivity, but it has been done on several occasions. Removing them from the wild was a far more common method of supplying the market demand.

They can be difficult pets to care for, requiring regular attention and a very specific diet of grasses and hay. Each year they go into a period called rut that can last for several months, in which their personalities can drastically change, often becoming defensive or even aggressive. Despite their needs, prairie dogs are very social animals and come to almost seem like they treat humans as members of their colony, answering barks and chirps, and even coming when called by name.

In mid-2003, due to cross-contamination at a Madison, Wisconsin-area pet swap from an unquarantined Gambian pouch rat imported from Ghana, several prairie dogs in captivity acquired monkeypox, and subsequently a few humans were also infected. This led the CDC to institute an outright ban on the sale, trade, and transport of prairie dogs within the United States. The disease was never introduced to any wild populations. The European Union also banned importation of prairie dogs in response. While largely seen by exotic pet owners and vendors as unfair, the monkeypox scare was not the only zoonosis incident associated with prairie dogs.

Prairie dogs are also very susceptible to bubonic plague, and many wild colonies have been wiped out by it. Also, in 2002 a large group of prairie dogs in captivity in Texas were found to have contracted tularemia. The prairie dog ban is frequently cited by the CDC as a successful response to the threat of zoonosis.

Prairie dogs that were in captivity at the time of the ban in 2003 were allowed to be kept under a grandfather clause, but were not to be bought, traded, or sold and transport was only permitted to and from a veterinarian under quarantined procedures.

On September 8, 2008, the FDA & CDC rescinded the ban making it once again legal to capture, sell, and transport prairie dogs effective immediately. Federal Register / Vol. 73, No. 174. Although the federal ban has been lifted, several States still have their own ban on prairie dogs in place.

Lemur

2009-06-30T07:26:00.000-07:00

Lemurs make up the infraorder Lemuriformes and are members of a group of primates known as strepsirrhines. The term "lemur" is derived from the Latin word lemures, meaning "spirits of the night" or "ghosts". This likely refers to their large, reflective eyes and the wailing cries of some species (the Indri in particular). The term is generically used for the members of the five lemuriform families, but it is also the genus of one of the lemuriform species, the Ring-tailed Lemur (Lemur catta). The two so-called flying lemur species, known formally as colugos, are not lemurs or even primates.

Lemurs are primates endemic to the island of Madagascar and smaller surrounding islands, such as the Comoros, where they were likely introduced by humans. Molecular genetics indicates that they reached Madagascar after it broke away from mainland Africa, possibly by "rafting" across the ocean on large clumps of vegetation. While their ancestors were displaced in the rest of the world by monkeys and apes, the lemurs were safe from competition on Madagascar and differentiated into a number of species. These range in size from the tiny 30 gram (1 oz) Pygmy Mouse Lemur to the 10 kilogram (22 lb) Indri. Larger species, some of which weighed up to 240 kg, have all become extinct since humans settled on Madagascar. Typically, the smaller lemurs are nocturnal, while the larger ones are diurnal.

The small cheirogaleoids are generally omnivores, eating a variety of fruits, flowers and leaves (and sometimes nectar) as well as insects, spiders and small vertebrates. The remainder of the lemurs - the lemuroids - are primarily herbivores, although some species supplement their diet with insects.

Except for the Indri, all lemurs have long tails that they use for communication with each other and balance when leaping between trees. They have opposable thumbs and long toes adapted for gripping tree branches. Lemurs have nails rather than claws on all digits except the second toe of each hind foot, which has a toilet-claw for grooming.

All lemur species have a tapetum, the reflective layer over the retina that enhances night vision. Lemurs are thought to have limited color vision. Lemurs depend heavily on the sense of smell and have large nasal cavities and moist noses.

Unlike most other primates, lemur species that live in groups have a matriarchal society (i.e., females are dominant over males). Most lemur species are arboreal and traverse the canopy by vertical clinging and leaping or quadrupedalism, with the exception of the Ring-Tailed Lemur, which spend more time on the ground than other species.

Hybrids may occur between different species of lemur. In The variation of animals and plants under domestication Charles Darwin noted: "Several members of the family of Lemurs have produced hybrids in the Zoological Gardens.

Many, but not all, lemur species exhibit female dominance, which is a very rare social structure in mammals, and it is only observed consistently in hyenas and lemurs. In species where this occurs, adult males exhibit submissive behavior to adult females in social settings, such as feeding, grooming, and sleeping site priority. Interestingly, most lemurs do not exhibit sexual dimorphism, but it remains unclear what role size and strength play in male deference. Although several hypotheses have been proposed to explain the evolution of female dominance in the last 20 years, the hypotheses have been unsatisfactory among researchers and there is currently no generally accepted hypothesis. A compelling and simple explanation, however, was recently introduced by Dunham who suggested that female dominance in lemurs arises from a combination of having similar sized sexes and higher resource needs of females for reproduction. Simple game theory states that in a contest between two individuals with similar fighting capacity, the contestant with higher resource need is likely to devote more energy into fighting for that resource.

Species 1 will be expected to win a contest when the simple inequality: V1/K1 > V2/K2, is met, where V is the value of the resource to the contestant in terms of fitness and K is the fighting capacity measured as a rate of fitness loss. Because male and female lemurs are of the same size, the fighting capacity should not differ. Therefore a contest between a male and a female lemur will most likely be decided by who has the higher resource need. With very short reproductive seasons and lack of male care, male lemurs are assumed to expend much less energy in reproduction relative to females (i.e. pregnancy, lactation, maternal care, etc.). As such, a female has more to lose in terms of fitness by not attaining the resource and is therefore more likely to win a contest with a male. Because fighting can be costly it may be beneficial for males if they can asses their chance of winning based on sex, thus submitting to females. Evidence supporting this hypothesis is also found in birds and other mammals.

Female social dominance was first observed in the Ring-tailed Lemur (Lemur catta). Since then, many, but not all, species of lemurs have been found to demonstrate female social dominance including the Crowned Lemur (Eulemur coronatus) and the Gray Mouse Lemur (Microcebus murinus).

Most lemurs are listed as endangered or threatened species. Many species have gone extinct in the last centuries, mainly due to habitat destruction (deforestation) and hunting. Conservation of lemurs in Madagascar is a high priority, but the country's poor economic situation and the lemurs' limited range make it an uphill battle. In 2008, a total of 99 living lemur species were formally recognized, with more species likely to be discovered or differentiated in the future.

One of the foremost lemur research facilities is the Duke Lemur Center. Also, Idea Wild (ideawild.org) has contributed to some projects on the conservation of different areas in Madagascar to prevent further deforestation. Idea Wild helps Malagasy farmers find more sustainable alternatives to slash and burn agriculture which destroys the habitat of the lemurs and other animals in Madagascar.

Tasmanian Devil

2009-06-28T16:00:00.000-07:00

The Tasmanian Devil (Sarcophilus harrisii) is a carnivorous marsupial now found in the wild only in the Australian island state of Tasmania. The Tasmanian Devil is the only extant member of the genus Sarcophilus. The size of a small dog, but stocky and muscular, the Tasmanian Devil is now the largest carnivorous marsupial in the world after the extinction of the Thylacine in 1936. It is characterised by its black fur, offensive odor when stressed, extremely loud and disturbing screech, and ferocity when feeding. It is known to both hunt prey and scavenge carrion and although it is usually solitary, it sometimes eats with other devils.

The Tasmanian Devil was extirpated on the Australian mainland about 400 years before European settlement in 1788.

Because they were seen as a threat to livestock in Tasmania, devils were hunted until 1941, when they became officially protected. Since the late 1990s devil facial tumour disease has reduced the devil population significantly and now threatens the survival of the species, which in May 2008 was declared to be endangered.

Programs are currently being undertaken by the Tasmanian government to reduce the impact of the disease.

The Tasmanian Devil is the largest surviving carnivorous marsupial in Australia. It has a squat and thick build, with a large head and a tail which is about half its body length. The devil stores body fat in its tail, so unhealthy devils often have thin tails. Unusually for a marsupial, its forelegs are slightly longer than its hind legs. Devils can run up to 13 km (8.1 mi) per hour for short distances. The fur is usually black, although irregular white patches on the chest and rump are common. Males are usually larger than females, having an average head and body length of 652 mm (25.7 in), with a 258 mm (10.2 in) tail, and an average weight of 8 kg (18 lb). Females have an average head and body length of 570 mm (22 in), with a 244 mm (9.6 in) tail, and an average weight of 6 kg (13 lb). The average life expectancy of a Tasmanian Devil in the wild is estimated at six years, although they may live longer in captivity.

The devil has long whiskers on its face and in clumps on the top of the head. These help the devil locate prey when foraging in the dark, and aid in detecting when other devils are close during feeding. When agitated, the devil can produce a strong odour, its pungency rivaling even the skunk. Hearing is its dominant sense, and it also has an excellent sense of smell. Since devils hunt at night, their vision seems to be strongest in black and white. In these conditions they can detect moving objects readily, but have difficulty seeing stationary objects. An analysis of mammalian bite force relative to the body size shows that the devil has the strongest bite of any living mammal (over 5,100 psi (35,000 kPa)). The power of the jaw is in part due to its comparatively large head. A Tasmanian Devil also has one set of teeth that grows slowly throughout its life.

Tasmanian Devils are widespread and fairly common throughout Tasmania, but are quickly dying from a face cancer.

Found in all habitats on the island, including the outskirts of urban areas, they particularly like dry sclerophyll forests and coastal woodlands. The Tasmanian Devil is a nocturnal and crepuscular hunter, spending the days in dense bush or in a hole. Young devils can climb trees, but this becomes more difficult as they grow larger.

Devils can also swim. They are predominantly solitary animals and do not form packs. They occupy territories of 8–20 km², which can overlap considerably amongst different animals.

Tasmanian Devils can take prey up to the size of a small kangaroo, but in practice they are opportunistic, and eat carrion more often than they hunt live prey. Although the devil favours wombats, it will eat all small native mammals, domestic mammals (including sheep), birds, fish, insects, frogs and reptiles. Their diet is largely varied and depends on the food available. On average, they eat about 15% of their body weight each day; however, they can eat up to 40% of their body weight in 30 minutes if the opportunity arises. Tasmanian Devils eliminate all traces of a carcass, devouring the bones and fur in addition to the meat and internal organs. In this respect, the devil has earned the gratitude of Tasmanian farmers, as the speed at which they clean a carcass helps prevent the spread of insects that might otherwise harm livestock.

Although they hunt alone, eating is a social event for the Tasmanian Devil. Much of the noise attributed to the animal is a result of raucous communal eating, at which up to 12 individuals can gather, and can often be heard several kilometers away. A study of feeding devils identified 20 physical postures, including their characteristic vicious yawn, and the 11 different vocal sounds that devils use to communicate as they feed. They usually establish dominance by sound and physical posturing, although fighting does occur. Adult males are the most aggressive, and scarring is common from fighting over food and mates.

For some time, Tasmania was the last refuge of large marsupial carnivores. All of the larger carnivorous marsupials became extinct in mainland Australia shortly after humans arrived. Only the smallest and most adaptable survived.

Fossil evidence from western Victoria shows that Tasmanian Devils retained a place on the Australian mainland until around 600 years ago (about 400 years before European colonisation). Their extinction is attributed to predation by dingoes and hunting by indigenous Australians. In dingo-free Tasmania, carnivorous marsupials were still active when Europeans arrived. The extermination of the Thylacine after the arrival of the Europeans is well known, but the Tasmanian Devil was threatened as well.

The first Tasmanian settlers ate Tasmanian Devil, which they described as tasting like veal. As it was believed devils would hunt and kill livestock, a bounty scheme to remove the devil from rural properties was introduced as early as 1830. Over the next 100 years, trapping and poisoning brought them to the brink of extinction. After the death of the last Thylacine in 1936, the threat to the devils was recognized. The Tasmanian Devil was protected by law in 1941 and the population slowly recovered.

At least two major population declines, possibly due to a disease epidemic, have occurred in recorded history: in 1909 and 1950. The Tasmanian Devil's current population is reported by Tasmania's Department of Primary Industries and Water as being in the range of 10,000 to 100,000 individuals, with 20,000 to 50,000 mature individuals being likely.

Senior Scientist for the Devil Facial Tumour Disease program Hamish McCallum offers a more conservative estimate of at least 20,000 individuals and at most 75,000.

The Tasmanian Devil is an iconic animal within Australia; it is the symbol of the Tasmanian National Parks and Wildlife Service, and the former Tasmanian Australian rules football team which played in the Victorian Football League was known as the Devils. The defunct Hobart Devils basketball team in the NBL was also named after the animal. The devil was one of six native Australian animals to appear on commemorative Australian two dollar coins issued between 1989 and 1994. Tasmanian Devils are popular with domestic and international tourists. Because of their unique personality the Tasmanian Devil has been the subject of numerous documentaries and non-fiction children's books. The most recent Australian documentary on the Tasmanian Devil, Terrors of Tasmania, directed and produced by David Parer and Elizabeth Parer-Cook, was released in 2005. The documentary follows a female devil called Manganinnie through breeding season and the birth and rearing of her young. The documentary also looks at the effect of devil facial tumor disease and the conservation measures being taken to ensure survival of the Tasmanian Devil. The documentary has screened on television in Australia and in the United States on the National Geographic Channel.

Restrictions on the export of the Tasmanian Devil means that devils can normally only be seen in captivity in Australia. The last known overseas devil died at the Fort Wayne Children's Zoo in 2004. However, the Tasmanian Government has sent a pair of devils to the Copenhagen Zoo, following the birth of the first son of Frederik, Crown Prince of Denmark and his Tasmanian wife Mary in October 2005. These are the only devils that can be seen outside Australia.

Mulgara

2009-06-19T14:28:00.000-07:00

Mulgaras are the two species in the Dasycercus genus. They are marsupial carnivores closely related to the Tasmanian Devil and the quolls that lives in deserts and spinifex bush of central Australia. They are 12.5-22 cm long with a 7-13 cm tail. They are nocturnal but occasionally "sunbathe" in the entrance of the burrow it dwells in. They tend to stay in places that have been in shadow. Their kidneys are highly developed to excrete extremely concentrated urine in order to preserve water, as the animals never drink. They feed mostly on insects, but also eat lizards and newborn snakes. They breed from June-September and have litters of 6-7 young. The pouch comprises two lateral folds of skin.

The genus once contained other species, but they have been removed to other genera, leaving only D. cristicauda. Recent research has shown that there are two distinct species. The two species are very similar and were only recently described as being distinct. The Brush-tailed Mulgara (D. blythi) synonymoous as D. hilleri has a non-crested tail, two upper premolars, and six nipples. The Crest-tailed Mulgara (D. cristicauda) has a crested tail, three upper premolars, and eight nipples.

Much is still to be learned about the mulgaras, such as their social behaviour.

The generic name Dasycercus means "hairy-tail".

The Brush-tailed Mulgara (Dasycercus blythi) is a large carnivorous Australian marsupial species. Its body mass is over 100grams, with males being slightly larger than females. Their head length is 15 cm, and tail length is 9 cm.

The taxonomy of the 'mulgaras' has been confusing but as of 2005/06 two species are recognized: this species and the Crest-tailed Mulgara.

Sand Dollar

2009-06-18T21:13:00.000-07:00

Sand dollars (order Clypeasteroida) are flat, round marine animals related to sea urchins (echinoids), sea stars, and other echinoderms. The most common sand dollar, Echinarachnius parma, is widespread in circumpolar ocean waters in the northern hemisphere, from the intertidal zone to considerable depths.

A sand dollar has a rigid skeleton known as a "test", and the word sand dollar is also used for the test when it is found washed up on the beach after the death of the animal. When sand dollars are living, they have a skin of moveable spines covering the entire test. Movement is accomplished by the coordinated action of the spines. Like its close relative the sea urchin, the sand dollar has a set of five paired rows of pores; in sand dollars they are arranged in a petal-like pattern. These pores are perforations in the endoskeleton through which the podia, used in gas exchange, project from the body.

The name "sand dollar" is a reference to its round flat shape, which is similar to a large coin. The term "sand dollar" can also refer to the test left when a sand dollar dies. By the time the test washes up on the beach, it is usually missing its velvety covering of minute spines and has a somewhat bleached and often slightly greenish appearance due to its exposure to the sun.

Like other echinoderms, sand dollars have fivefold radial symmetry (pentamerism). Unlike other sea urchins, the sand dollar has developed a secondary bilateral symmetry, with a front and back as well as a top and bottom: this is a result of the flattening of the test in the sand dollar's evolutionary transition from a lifestyle on top of the substrate to that of a burrowing animal. The anus is toward the rear rather than on the top, as normally with other sea urchins.

Sand dollars live beyond mean low water on top of or just beneath the surface of sandy or muddy areas. The spines on the somewhat flattened underside of the animal allow it to burrow or to slowly creep through the sand. Fine, hair-like cilia cover the tiny spines. Tubefeet or podia that line the food grooves, move food to the mouth opening which is in the center of the star shaped grooves on the underside of the animal called the oral surface. Its food consists of crustacean larvae, small copepods, detritus, diatoms, algae and organic particles that end up in the sandy bottom.

On the ocean bottom, sand dollars are frequently found together. This is due in part to their preference for soft bottom areas, which are convenient for their reproduction. The sexes are separate and, as with most echinoids, gametes are released into the water column. The free-swimming larvae metamorphose through several stages before the skeleton or test begins to form, at which point they become bottom dwellers.

Live sand dollars can be greenish, bluish or purple. Their highly modified spines and tubefeet give them a velvety feel and appearance.

The ancestors of the sand dollars diverged from the other irregular echinoids, namely the cassiduloids, during the early Jurassic, with the first true sand dollar genus, Togocyamus, arising during the Paleocene. Soon after Togocyamus, more modern-looking groups emerged during the Eocene, 40 million years ago.

In 2008, scientists showed that sand dollar larvae can clone themselves as a mechanism of self defense. Larvae exposed to mucus from predatory fish cloned themselves, effectively halving their size. The smaller larvae are believed to better escape detection from fish predators, but may increase the danger of predation from smaller animals, such as crustaceans.

If you've strolled along a beach in Maine, you've probably found a sand dollar. But what is a sand dollar? Children have been known to say that sand dollars are pressed sand that has been dried or even the money of mermaids washed-up from the deep. In reality, the fragile disk is the skeleton or "test" of a marine animal. By the time the test washes up on the beach it is missing its velvety covering of minute spines and appears somewhat bleached from the sun. It is hard to believe it was once alive.

Sand dollars are from the class of marine animals known as Echinoids, spiny skinned creatures. Their relations include the sea lily, the sea cucumber, the star fish and the sea urchin. When alive, the local species, Echinarachnius parma is outfitted in a maroon-colored suit of moveable spines that encompass the entire shell. Like its close relative the sea urchin, the sand dollar has five sets of pores arranged petal pattern. The pores are used to move sea water into its internal water-vascular system which allows for movement.

Ray

2009-06-18T16:06:00.000-07:00

The manta ray (Manta birostris), is the largest of the rays, with the largest known specimen having been more than 7.6 m (about 25 ft) across, with a weight of about 2,300 kg (about 5,000 lb). It ranges throughout tropical waters of the world, typically around coral reefs.

Mantas have been given a variety of common names, including Atlantic manta, Pacific manta, devilfish, and just manta. Recent studies have suggested that what is called manta ray are at least two different species, one smaller local and one much larger and migratory.

Manta rays may have evolved from bottom-feeders, and then adapted to become filter feeders in the open ocean. This allowed them to grow larger than other ray species. Due to being plankton feeders, some of the ancestral characteristics have degenerated. For example, all that is left of their oral teeth is a small band of vestigial teeth on the lower jaw, almost hidden by the skin. Their dermal denticles are also greatly reduced in number and size but are still present. They have a much thicker body mucus coating than other rays. Their spiracles have become small and non-functional, as all water is taken in through their mouth instead.

Taxonomically, mantas are under investigation. Three species are identified: Manta birostris, Manta ehrenbergii, and Manta raya. They are quite similar, and the latter two may just be isolated populations. The genus Manta is sometimes placed in its own family, Mobulidae, but this article follows FishBase taxonomy and places it in the family Myliobatidae, along with eagle rays and their relatives.

Mantas are filter feeders: they feed on plankton, fish larvae and the like, passively filtered from the water passing through their gills as they swim. Small prey organisms are caught on flat horizontal plates of russet-coloured spongy tissue spanning spaces between the manta's gill bars.

Mantas frequent reef-side cleaning stations where small fish such as wrasses and angelfish swim in the manta's gills and over its skin to feed, in the process cleaning it of parasites and removing dead skin.

The predators of the Manta ray are mainly large sharks, however in some circumstances orcas have also been observed preying on them.

Mantas are extremely curious around humans, and are fond of swimming with scuba divers. Although they may approach humans, if touched, their mucus membrane is removed, causing lesions and infections on their skin. They often surface to investigate boats without engines running. They have the largest brain-to-body ratio of the sharks and rays.

Mantas are known to breach the water into the air.

The Moche people of ancient Peru worshipped the sea and its animals. They often depicted Manta rays in their art. Not knowing about their gentle nature, two movies of the 1930s played on the manta's "fearsome" appearance: 1930's The Sea Bat, starring a pre-Frankenstein Boris Karloff, and 1936's The Sea Fiend, later re-issued as the 1946 Devil Monster.

In modern times, the manta ray continues to serve as a source of inspiration. For example, the manta ray is the namesake of the Tampa Bay Rays Major League Baseball team, and the team's original name was the Devil Rays, one of the manta's alternate names. In 2009, SeaWorld Orlando debuted Manta, a flying roller coaster themed to resemble the manta ray, along with an exhibit featuring other ray species.

Manta rays are very rarely kept in captivity, primarily due to their size. Only four aquariums in the world have manta rays on display. One notable example is "Nandi", a manta ray that was accidentally caught in shark nets off Durban, South Africa in 2007. Rehabilitated, and outgrowing her aquarium, uShaka Marine World, Nandi was transferred to the larger Georgia Aquarium in August 2008, where she resides in its 6.2-million-gallon "Ocean Voyager" exhibit.

Aye-aye

2009-06-17T19:20:00.000-07:00

The Aye-aye (Daubentonia madagascariensis) is a strepsirrhine native to Madagascar that combines rodent-like teeth with a long, thin middle finger to fill the same ecological niche as a woodpecker. It is the world's largest nocturnal primate, and is characterized by its unusual method of finding food; it taps on trees to find grubs, then gnaws holes in the wood and inserts its elongated middle finger to pull the grubs out. The only other animals known to find food in this way is the Striped Possum. From an ecological point of view the Aye-aye fills the niche of a woodpecker as it is capable of penetrating wood to extract the invertebrates within.

Daubentonia is the only genus in the family Daubentoniidae and infraorder Chiromyiformes. The Aye-aye is the only extant member of the genus (although it is currently classified as Near Threatened by the IUCN); a second species, Daubentonia robusta, appears to have become extinct at some point within the last 1000 years.

The Aye-aye is the world's largest nocturnal prosimian, and dwells predominantly in forest canopies. It weighs about 2.5 kilograms, with the female weighing in slightly less (by an average of 100 grams) than males. Other than weight and sex organs, aye-ayes exhibit no sexual dimorphism of any kind. They all grow from 30-37 cm from head to body, with a 44-53 cm tail.

The adult Aye-aye has black or dark brown fur covered by white guard hairs at the neck. The tail is bushy and shaped like that of a squirrel. The Aye-aye's face is also rodent-like, the shape of a raccoon's, and has bright, beady, luminous eyes. Its incisors are very large, and grow continuously throughout its lifespan. These features contrast its monkey-like body, and are the likely cause of why scientists originally deemed it to be a rodent.

The Aye-aye's hands are arguably its most unusual feature. Much like other primates, it possesses opposable thumbs, but both the hallux and the fingers are long and slender, and appear to be in a curved position somewhat similar to that of a fairy-tale witch when the muscles are relaxed. The middle finger can be up to three times longer than the others.

Gestation for the Aye-aye lasts from 5 to 5 1/3 months. Births can occur at any time during the year, and females often wait 2–3 years between births. The infant takes about 7 months to be weaned, and stays with its mother for two years. The Aye-aye matures quickly; males rarely take more than 1 1/2 years to mature, and females take about an extra year. Lifespan is not known, but the world record is 23 years in captivity.

The Aye-aye lives primarily on the east coast of Madagascar. Its natural habitat is rainforest or deciduous forest, but many live in cultivated areas due to deforesting. Rainforest Aye-ayes, the most common, dwell in canopy areas, and are usually sighted upwards of 700 meters altitude. The Aye-aye sleeps during the day in nests built in the forks of trees.

The Aye-aye is classically considered 'solitary', but recent research suggests that they are more social than once thought. It usually sticks to foraging in its own personal home range, or territory. The home ranges of males often overlap and the males can be very social with each other. Female home ranges never overlap, though a male's home range often overlaps that of several females. The male Aye-Aye live in large areas that are up to 80 acres (320,000 m2) while female have smaller living space that goes up to 20 acres (81,000 m2). Regular scent marking with their cheeks, neck and genitals is a way that aye-ayes let others know of their presence and repel intruders from their territory. Like many other prosimians, the female Aye-aye is dominant to the male. The Aye-aye is not monogamous by any means, and often competes with each other for mates. Males are very aggressive in this regard, and sometimes even pull other males off a female during mating. Outside of mating, males and females interact only occasionally, usually while foraging.

After impregnating a female, the male usually stays in close proximity until the infant is born and has matured a bit. The father will sometimes share food with the infant, but otherwise infants' primary source of social interaction is with their mothers. Mothers and infants often wrestle, chase, and play "peek-a-boo" for entertainment. After 13 weeks, infants are usually ready to interact with other young Aye-ayes, usually by play-fighting.

The Aye-aye begins foraging anywhere between 30 minutes before or 3 hours after sunset. Up to 80% of the night is spent foraging in the canopy, separated by occasional rest periods. The monkey-like body of the Aye-aye enables it to move vertically with ease. It climbs trees by making successive vertical leaps, much like a squirrel.

Horizontal movement is more difficult, but the Aye-aye rarely descends to jump to another tree, and can often cross up to 4 kilometers a night.

Infants are fully dextrous within a month of birth. At first they can only climb on a branch hanging upside down, but they gradually work their way up to the various acrobatic feats that adults can perform. Curiously, walking and running on the ground is often hardest for an Aye-aye to master.

The Aye-aye commonly eats nuts, and also grubs, fruits, nectar, seeds, and fungi, classifying it as an omnivore. It often picks fruit off trees as it moves through the canopy, often barely stopping to do so. An Aye-aye not lucky enough to live in its natural habitat will often steal coconuts, mangoes, sugar cane, lychees and eggs from villages and plantations. Aye-ayes chew a hole into wood and get grubs out of that hole with their elongated and bony middle fingers.

The Aye-aye is an endangered species not only because its habitat is being destroyed, but also due to native superstition. Besides being a general nuisance in villages, ancient Malagasy legend said that the Aye-aye was a symbol of death. It is viewed as a good omen in some areas, however, but these areas are a minority.

Rhinoceros

2009-06-15T15:20:00.000-07:00

Rhinoceros (pronounced /raɪˈnɒsərəs/), often colloquially abbreviated rhino, is a name used to group five extant species of odd-toed ungulates in the family Rhinocerotidae. Two of these species are native to Africa and three to southern Asia. Three of the five species—the Javan, Sumatran and Black Rhinoceros—are critically endangered. The Indian is endangered, with fewer than 2,700 individuals remaining in the wild. The White is registered as Vulnerable, with over 9,000 remaining in the wild.

The white rhino is actually not white at all. The name comes from "wide" referring to the wide square mouth that allows the rhino to eat broads of grass.

The rhinoceros family is characterized by its large size (one of the largest remaining megafauna alive today), with all of the species able to reach one ton or more in weight; herbivorous diet; and a thick protective skin, 1.5–5 cm thick, formed from layers of collagen positioned in a lattice structure; relatively small brains for mammals this size (400–600g); and a large horn. They generally eat leafy material, although their ability to ferment food in their hindgut allows them to subsist on more fibrous plant matter, if necessary. Unlike other perissodactyls, the African species of rhinoceros lack teeth at the front of their mouths, relying instead on their powerful premolar and molar teeth to grind up plant food.

The rhino is prized for its horn. The horns of a rhinoceros are made of keratin, the same type of protein that makes up hair and fingernails. Both African species and the Sumatran Rhinoceros have two horns, while the Indian and Javan Rhinoceros have a single horn.

Rhinoceroses have acute hearing and sense of smell, but poor eyesight. Most live to be about 60 years old or more.

The White Rhinoceros or Square-lipped Rhinoceros (Ceratotherium simum) is, after the elephant, the most massive remaining land animal in the world, along with the Indian Rhinoceros and the hippopotamus, which are of comparable size. There are two subspecies of White Rhinos; as of 2005, South Africa has the most of the first subspecies, the Southern White Rhinoceros (Ceratotherium simum simum). The population of Southern White Rhinos is about 14,500, making them the most abundant subspecies of rhino in the world. However, the population of the second subspecies, the critically-endangered Northern White Rhinoceros (Ceratotherium simum cottoni), is down to as few as four individuals in the wild, and as of June 2008 this sub-species could even be extinct.

The White Rhino has an immense body and large head, a short neck and broad chest. This rhino can exceed 3000 kg (6600 pounds), have a head-and-body length of 3.35-4.2 m (11-13.9 feet) and a shoulder height of 150-185 cm (60-73 inches). The record-sized White Rhinoceros was about 4500 kg (10,000 lb). On its snout it has two horns. The front horn is larger than the other horn and averages 89.9 cm (23.6 inches) in length and can reach 150 cm (59 inches).

The White Rhinoceros also has a noticeable hump on the back of its neck which supports its large head. The colour of this animal ranges from yellowish brown to slate grey. The only hair on them is on the ear fringes and tail bristles with little across the body. White Rhinos have the distinctive flat broad mouth which is used for grazing.

The name Black Rhinoceros (Diceros bicornis) was chosen to distinguish this species from the White Rhinoceros (Ceratotherium simum). This can be confusing, as those two species are not really distinguishable by colour.

There are four subspecies of black rhino: South-central (Diceros bicornis minor), the most numerous, which once ranged from central Tanzania south through Zambia, Zimbabwe and Mozambique to northern and eastern South Africa; South-western (Diceros bicornis bicornis) which are better adapted to the arid and semi-arid savannas of Namibia, southern Angola, western Botswana and western South Africa; East African (Diceros bicornis michaeli), primarily in Tanzania; and West African (Diceros bicornis longipes) which was tentatively declared extinct in 2006. Only 8 of this subspecies are left in existence, all in captivity.

An adult Black Rhinoceros stands 147–160 cm (57.9–63 inches) high at the shoulder and is 3.3-3.6 m (10.8–11.8 feet) in length. An adult weighs from 800 to 1400 kg (1,760 to 3,080 lb), exceptionally to 1820 kg (4,000 lb), with the females being smaller than the males. Two horns on the skull are made of keratin with the larger front horn typically 50 cm long, exceptionally up to 140 cm. Sometimes, a third smaller horn may develop. The Black Rhino is much smaller than the White Rhino, and has a pointed mouth, which they use to grasp leaves and twigs when feeding.

The Indian Rhinoceros or the Great One-horned Rhinoceros (Rhinoceros unicornis) is now found almost exclusively in Nepal and North-Eastern India. The rhino once inhabited many areas of Pakistan to Burma and may have even roamed in China. But because of human influence their range has shrunk and now they only exist in several protected areas of India (in Assam, West Bengal and a few pairs in Uttar Pradesh) and Nepal, plus a few pairs in Lal Suhanra national park in Pakistan. It is confined to the tall grasslands and forests in the foothills of the Himalayas.

The Indian Rhinoceros has thick, silver-brown skin which creates huge folds all over its body. Its upper legs and shoulders are covered in wart-like bumps, and it has very little body hair. Fully-grown males are larger than females in the wild, weighing from 2200–3000 kg (4,800–6,600 lb). Female Indian rhinos weigh about 1600 kg. The Indian Rhino is from 5.7–6.7 feet tall and can be up to 13 feet (4.0 m) long. The record-sized specimen of this rhino was approximately 3500 kg. The Indian Rhino has a single horn that reaches a length of between 20 and 101 cm. Its size is comparable to that of the White Rhino in Africa.

Two-thirds of the world's Great One-horned Rhinoceroses are now confined to the Kaziranga National Park situated in the Golaghat district of Assam, India.

The Javan Rhinoceros (Rhinoceros sondaicus) is one of the rarest and most endangered large mammals anywhere in the world. According to 2002 estimates, only about 60 remain, in Java (Indonesia) and Vietnam. Of all the rhino species, the least is known of the Javan Rhino.

These animals prefer dense lowland rain forest, tall grass and reed beds that are plentiful with large floodplains and mud wallows. Though once widespread throughout Asia, by the 1930s the rhinoceros was nearly hunted to extinction in India, Burma, Peninsular Malaysia, and Sumatra for the supposed medical powers of its horn and blood.

Like the closely related larger Indian Rhinoceros, the Javan rhinoceros has only a single horn. Its hairless, hazy gray skin falls into folds into the shoulder, back, and rump giving it an armored-like appearance. The Javan rhino's body length reaches up to 3.1-3.2 m (10-10.5 feet), including its head and a height of 1.5–1.7 m (4.9-5.6ft)tall. Adults are variously reported to weigh between 900–1,400 kg or 1,360-2,000 kg. Horns of males can reach 26 cm in length while in females they are knobs or no horn at all.

The Sumatran Rhinoceros (Dicerorhinus sumatrensis) is the smallest extant rhinoceros species, as well as the one with the most fur, which allows it to survive at very high altitudes in Borneo and Sumatra. Due to habitat loss and poaching, its numbers have declined and it is one of the world's rarest mammals. About 275 Sumatran Rhinos are believed to remain.

Typically a mature Sumatran rhino stands about 130 cm (4.3ft) high at the shoulder, a body length of 240–315 cm (7.9ft - 10.3ft) and weighs around 700 kg (1543 lbs), though the largest individuals have been known to weigh as much as 1,000 kilograms. Like the African species, it has two horns; the largest is the front (25–79 cm) and the smaller being the second, which is usually less than 10 cm long. The males have much larger horns than the females. Hair can range from dense (the most dense hair in young calves) to scarce. The color of these rhinos is reddish brown. The body is short and has stubby legs. They also have a prehensile lip.

Rhinocerotoids diverged from other perissodactyls by the early Eocene. Fossils of Hyrachyus eximus found in North America date to this period. This small hornless ancestor resembled a tapir or small horse more than a rhino.

Three families, sometimes grouped together as the superfamily Rhinocerotoidea, evolved in the late Eocene: Hyracodontidae, Amynodontidae and Rhinocerotidae.

Hyracodontidae, also known as "running rhinos," showed adaptations for speed, and would have looked more like horses than modern rhinos. The smallest hyracodontids were dog-sized; the largest was Indricotherium, believed to be one of the largest land mammals that ever existed.

The hornless Indricotherium was almost seven meters high, ten meters long, and weighed as much as 15 tons. Like a giraffe, it ate leaves from trees. The Hyracodontids spread across Eurasia from the mid-Eocene to early Miocene.

The family Amynodontidae, also known as "aquatic rhinos," dispersed across North America and Eurasia, from the late Eocene to early Oligocene. The amynodontids were hippopotamus-like in their ecology and appearance, inhabiting rivers and lakes, and sharing many of the same adaptations to aquatic life as hippos.

The family of all the modern rhinoceroses, the Rhinocerotidae, first appeared in the Late Eocene in Eurasia. The earliest members of Rhinocerotidae were small and numerous; at least 26 genera lived in Eurasia and North America until a wave of extinctions in the middle Oligocene wiped out most of the smaller species. Several independent lineages survived, however.

Menoceras, a pig-sized rhinoceros which had two horns side-by-side or the Teleoceras of North America which had short legs and a barrel chest and lived until about 5 million years ago. The last rhinos in America became extinct during the Pliocene.

Modern rhinos are believed to have dispersed from Asia beginning in the Miocene. Two species survived the most recent period of glaciation and inhabited Europe as recently as 10,000 years ago. The woolly rhinoceros appeared in China around 1 million years ago and first arrived in Europe around 600,000 years ago and again 200,000 years ago, where alongside the woolly mammoth, they became numerous but eventually were hunted to extinction by early humans.

Another species of enormous rhino, Elasmotherium, survived the last ice age. Also known as the giant rhinoceros, Elasmotherium was two meters tall, five meters long and weighed around five tons, with a single enormous horn, hypsodont teeth and long legs for running.

Of the extant rhinoceros species, the Sumatran Rhino is the most archaic, first emerging more than 15 million years ago. The Sumatra Rhino was closely related to the woolly rhinoceros, but not to the other modern species. The Indian Rhino and Javan Rhino are closely related and from a more recent lineage of Asian rhino. The ancestors of early Indian and Javan rhino emerged 2-4 million years ago.

The origin of the two living African rhinos can be traced back to the late Miocene (6 mya) species Ceratotherium neumayri. The lineages containing the living species diverged by the early Pliocene (1.5 mya), when Diceros praecox, the likely ancestor of the Black Rhinoceros, appears in the fossil record. The black and white rhinoceros remain so closely related that they can still mate and successfully produce offspring.

In the wild, the adult black or white rhino has no natural predators other than humans but, although it is of massive size and has a reputation of being tough, it is actually very easy to be poached. While visiting water holes daily the rhinoceros is easily killed while taking a drink. As the rhinoceros population is constantly decreasing, efforts are being made to stop the poaching of the rhinos.

Snake

2009-06-14T14:21:00.000-07:00

Snakes are elongate legless carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic amniote vertebrates covered in overlapping scales. Like lizards, from which they evolved, they have loosely articulated skulls and most can swallow prey much larger than their own head. In order to accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca.

Living snakes are found on every continent except Antarctica. Fifteen families are currently recognized comprising 456 genera and over 2,900 species. They range in size from the tiny, 10 cm long thread snake to pythons and anacondas of up to 7.6 m (25 ft) in length. The recently discovered fossil Titanoboa was 13 m or 43 ft long.

Snakes are thought to have evolved from either burrowing or aquatic lizards during the Cretaceous period (c 150 Ma). The diversity of modern snakes appeared during the Paleocene period (c 66 to 56 Ma).

Most species are non-venomous and those that have venom use it primarily to kill and subdue prey rather than for self-defense. Some possess venom potent enough to cause painful injury or death to humans.

The English word snake comes from Old English snaca, itself from Proto-Germanic *snak-an- (cf. German Schnake "ring snake", Swedish snok "snake"), from Proto-Indo-European root *(s)nēg-o- "to crawl, creep", which also gave sneak as well as Sanskrit nāgá "snake". The word ousted adder as it went on to narrow in meaning, though in Old English næddre was the general word for snake. Another term, serpent, was borrowed from Old French, ultimately from Indo-European *serp- "to creep" which also gave Greek érpein (ερπω), to crawl.

The fossil record of snakes is relatively poor because snake skeletons are typically small and fragile, making fossilization uncommon. However 150 million-year-old specimens, readily identifiable as snakes, yet with lizard-like skeletal structures, have been uncovered in South America and Africa. There is consensus, on the basis of comparative anatomy, that snakes descended from lizards. Fossil evidence suggests that snakes may have evolved from burrowing lizards, such as the varanids or a similar group during the Cretaceous Period. An early fossil snake, Najash rionegrina, was a two-legged burrowing animal with a sacrum, and was fully terrestrial. One extant analog of these putative ancestors is the earless monitor Lanthanotus of Borneo, although it also is semi-aquatic.

Subterranean forms evolved bodies that were streamlined for burrowing and lost their limbs. According to this hypothesis, features such as the transparent, fused eyelids (brille) and loss of external ears evolved to cope with fossorial difficulies such as scratched corneas and dirt in the ears. Some primitive snakes are known to have possessed hindlimbs, but their pelvic bones lack a direct connection to the vertebrae. These include fossil species like Haasiophis, Pachyrhachis and Eupodophis, which are slightly older than Najash.

Primitive groups among the modern snakes, pythons and boas, have vestigial hind limbs; tiny, clawed digits known as anal spurs which are used to grasp during mating. Leptotyphlopidae and Typhlopidae are other groups where remnants of the pelvic girdle are present, sometimes appearing as horny projections when visible. The frontal limbs are non-existent in all snakes and this loss is associated with the evolution of the Hox genes controlling limb morphogenesis.

The axial skeleton of the snakes' common ancestor, like most other tetrapods had regional specializations consisting of cervical (neck), thoracic (chest), lumbar (lower back), sacral (pelvic) and caudal (tail) vertebrae. The Hox gene expression in the axial skeleton responsible for the development of the thorax became dominant early in snake evolution and as a result, the vertebrae anterior to the hindlimb buds (when present) all have the same thoracic-like identity (except from the atlas, axis and one to three neck vertebrae), making most of the snake's skeleton being composed of an extremely extended thorax. Ribs are found exclusively on the thoracic vertebrae. The neck, lumbar and pelvic vertebrae are very reduced in number (only two to ten lumbar and pelvic vertebrae are still present), while only a short tail remains of the caudal vertebrae, although the tail is still long enough to be of good use in many species, and is modified in some aquatic and tree dwelling species.

An alternative hypothesis, based on morphology, suggests that the ancestors of snakes were related to mosasaurs — extinct aquatic reptiles from the Cretaceous — which in turn are thought to have derived from varanid lizards.

Under this hypothesis, the fused, transparent eyelids of snakes are thought to have evolved to combat marine conditions (corneal water-loss through osmosis), while the external ears were lost through disuse in an aquatic environment, ultimately leading to an animal similar in appearance to sea snakes of today. In the Late Cretaceous, snakes re-colonized land to appear as they are today. Fossil snake remains are known from early Late Cretaceous marine sediments, which is consistent with this hypothesis, particularly as they are older than the terrestrial Najash rionegrina. Similar skull structure; reduced/absent limbs; and other anatomical features found in both mosasaurs and snakes lead to a positive cladistical correlation, although some of these features are shared with varanids. In recent years, genetic studies have indicated that snakes are not as closely related to monitor lizards as it was once
believed, and therefore not to mosasaurs, the proposed ancestor in the aquatic scenario of their evolution.

However, there is more evidence linking mosasaurs to snakes than to varanids. Fragmentary remains that have been found from the Jurassic and Early Cretaceous indicate deeper fossil records for these groups, which may eventually refute either hypothesis.

The great diversity of modern snakes appeared in the Paleocene, correlating with the adaptive radiation of mammals following the extinction of the non-avian dinosaurs. One of the more common groups today, the colubrids, became particularly diverse due to their preying on rodents, a mammal group that has been particularly successful. There are over 2,900 species of snakes ranging as far northward as the Arctic Circle in Scandinavia and southward through Australia and Tasmania. Snakes can be found on every continent (with the exception of Antarctica), dwelling in the sea, and as high as 16,000 feet (4,900 m)in the Himalayan Mountains of Asia. There are numerous islands from which snakes are conspicuously absent such as Ireland, Iceland, and New Zealand.

The skeleton of most snakes consists solely of the skull, hyoid, vertebral column, and ribs, though henophidian snakes retain vestiges of the pelvis and rear limbs. The skull of the snake consists of a solid and complete braincase, to which many of the other bones are only loosely attached, particularly the highly mobile jaw bones, which facilitate manipulation and ingestion of large prey items. The left and right sides of the lower jaw are joined only by a flexible ligament at the anterior tips, allowing them to separate widely, while the posterior end of the lower jaw bones articulate with a quadrate bone, allowing further mobility. The bones of the mandible and quadrate bones can also pick up ground borne vibrations. The hyoid is a small bone located posterior and ventral to the skull, in the 'neck' region, which serves as an attachment for muscles of the snake's tongue, as it does in all other tetrapods.

The vertebral column consists of anywhere between 200 to over 400 vertebrae. Tail vertebrae are comparatively few in number (often less than 20% of the total) and lack ribs, while body vertebrae each have two ribs articulating with them. The vertebrae have projections that allow for strong muscle attachment enabling locomotion without limbs.

Autotomy of the tail, a feature found in some lizards is absent in most snakes. Caudal autotomy in snakes is rare and is intervertebral unlike that seen in lizards which is intravertebral, that is, the break happens along a predefined fracture plane present on a vertebra.

The now extinct Titanoboa cerrejonensis snakes found were between 12 and 15 meters (39 and 49 ft) in length. In comparison, the largest extant snakes are the reticulated python, which measures about 9 meters (30 ft) long, and the anaconda, which measures about 7.5 meters (25 ft) long and is considered the heaviest snake on Earth. At the other end of the scale, the smallest extant snake is Leptotyphlops carlae with a length of about 10 centimeters (4 in).

The skin of a snake is covered in scales. Contrary to the popular notion of snakes being slimy because of possible confusion of snakes with worms, snakeskin has a smooth, dry texture. Most snakes use specialized belly scales to travel, gripping surfaces. The body scales may be smooth, keeled, or granular. The eyelids of a snake are transparent "spectacle" scales which remain permanently closed, also known as brille.

The shedding of scales is called ecdysis, or, in normal usage moulting or sloughing. In the case of snakes, the complete outer layer of skin is shed in one layer. Snake scales are not discrete but extensions of the epidermis hence they are not shed separately, but are ejected as a complete contiguous outer layer of skin during each moult, akin to a sock being turned inside out.

The shape and number of scales on the head, back and belly can be characteristic are often used for taxonomic purposes. Scales are named mainly according to their positions on the body. In "advanced" (Caenophidian) snakes, the broad belly scales and rows of dorsal scales correspond to the vertebrae, allowing scientists to count the vertebrae without dissection. Snake's eyes are covered by their clear scales rather than movable eyelids; therefore, their eyes are always open.

Moulting is repeated periodically throughout a snake's life. Before a moult, the snake stops eating and often hides or moves to a safe place. Just before shedding, the skin becomes dull and dry looking and the eyes become cloudy or blue-colored. The inner surface of the old outer skin liquefies. This causes the old outer skin to separate from the new inner skin. After a few days, the eyes clear and the snake "crawls" out of its old skin. The old skin breaks near the mouth and the snake wriggles out aided by rubbing against rough surfaces. In many cases the cast skin peels backward over the body from head to tail, in one piece like an old sock. A new, larger, and brighter layer of skin has formed underneath.

An older snake may shed its skin only once or twice a year, but a younger, still-growing snake, may shed up to four times a year. The discarded skin gives a perfect imprint of the scale pattern and it is usually possible to identify the snake if this discard is reasonably complete and intact. This periodic renewal has led to the snake being a symbol of healing and medicine, as pictured in the Rod of Asclepius.

Snake vision varies greatly, from only being able to distinguish light from dark to keen eyesight, but the main trend is that their vision is adequate although not sharp, and allows them to track movements. Generally, vision is best in arboreal snakes and weakest in burrowing snakes. Some snakes, such as the Asian vine snake (genus Ahaetulla), have binocular vision, with both eyes capable of focusing on the same point. Most snakes focus by moving the lens back and forth in relation to the retina, while in the other amniote groups, the lens is stretched.

Snakes use smell to track their prey. It smells by using its forked tongue to collect airborne particles then passing them to the Jacobson's organ or the Vomeronasal organ in the mouth for examination. The fork in the tongue gives the snake a sort of directional sense of smell and taste simultaneously. The snake keeps its tongue constantly in motion, sampling particles from the air, ground, and water analyzing the chemicals found and determining the presence of prey or predators in its local environment.

The part of the body which is in direct contact with the surface of the ground is very sensitive to vibration, thus a snake is able to sense other animals approaching through detecting faint vibrations in the air and on the ground.

Pit vipers, pythons, and some boas have infrared-sensitive receptors in deep grooves between the nostril and eye, although some have labial pits on their upper lip just below the nostrils (common in pythons) which allow them to "see" the radiated heat. Infrared sensitivity helps snakes locate nearby prey, especially warm-blooded mammals.

Snakes do not ordinarily prey on humans and most will not attack humans unless the snake is startled or injured, preferring instead to avoid contact. With the exception of large constrictors, non-venomous snakes are not a threat to humans. The bite of non-venomous snakes is usually harmless because their teeth are designed for grabbing and holding, rather than tearing or inflicting a deep puncture wound. Although the possibility of an infection and tissue damage is present in the bite of a non-venomous snake, venomous snakes present far greater hazard to humans.

In the Western world some snakes, especially docile species such as the ball python and corn snake, are kept as pets. To supply this demand a captive breeding industry has developed. Snakes bred in captivity tend to make better pets and are considered preferable to wild caught specimens. Snakes can be very low maintenance pets, especially in comparison to more traditional species. They require minimal space, as most common species do not exceed five feet in length. Pet snakes can be fed relatively infrequently, usually once every five to fourteen days. Certain snakes have a life span of more than forty years if given proper care.

Squirrel

2009-06-14T13:03:00.000-07:00

A squirrel is one of many small or medium-sized rodents in the family Sciuridae. In the English-speaking world, squirrel commonly refers to members of this family's genera Sciurus and Tamiasciurus, which are tree squirrels with large bushy tails, indigenous to Asia, the Americas and Europe. Similar genera are found in Africa. The Sciuridae family also include flying squirrels, as well as ground squirrels such as the chipmunks, prairie dogs, and woodchucks. Members of the family Anomaluridae are sometimes misleadingly referred to as "scaly-tailed flying squirrels" although they are not closely related to the true squirrels.

In USA and Canada common squirrels include the Fox Squirrel (S. niger); the Western Gray Squirrel (S. griseus); the Douglas Squirrel (Tamiasciurus douglasii); the American Red Squirrel T. hudsonicus; and the Eastern Grey Squirrel (S. carolinensis), of which the "Black Squirrel" is a variant. In Europe the Red Squirrel or Eurasian red squirrel (Sciurus vulgaris) is the most common native species, although the Eastern Grey Squirrel (S. carolinensis) has been introduced in some countries and has displaced the red in many areas including most of Britain.

The word squirrel, first attested in 1327, comes via Anglo-Norman esquirel from the Old French escurel, the reflex of a Latin word sciurus which was itself borrowed from Greek. The word itself comes from the Greek word σκιουρος, skiouros, which means shadow-tailed, because they use their tail to shade their whole body.

The native Old English word, ācweorna, only survived into Middle English (as aquerna) before being replaced. The Old English word is of Common Germanic origin, with cognates such as German Eichhorn/Eichhörnchen and Norwegian ekorn.

Unlike rabbits or deer, squirrels cannot digest cellulose and must rely on foods rich in protein, carbohydrates, and fat. In temperate regions early spring is the hardest time of year for squirrels, since buried nuts begin to sprout and are no longer available for the squirrel to eat, and new food sources have not become available yet. During these times squirrels rely heavily on the buds of trees. Squirrels' diet consists primarily of a wide variety of plant food, including nuts, seeds, conifer cones, fruits, fungi and green vegetation. However some squirrels also consume meat, especially when faced with hunger. Squirrels have been known to eat insects, eggs, small birds, snakes and rodents.

Ground and tree squirrels are typically diurnal, while flying squirrels tend to be nocturnal – except for lactating flying squirrels and their offspring, which have a period of diurnality during the summer.

Predatory behavior by various species of ground squirrels, particularly the thirteen-lined ground squirrel, has been noted. Bailey, for example, observed a thirteen-lined ground squirrel preying upon a young chicken. Wistrand reported seeing this same species eating a freshly killed snake. Whitaker examined the stomachs of 139 thirteen-lined ground squirrels, and found bird flesh in four of the specimens and the remains of a short-tailed shrew in one; Bradley, examining white-tailed antelope squirrels' stomachs, found at least 10% of his 609 specimens' stomachs contained some type of vertebrate — mostly lizards and rodents. Morgart (1985) observed a white-tailed antelope squirrel capturing and eating a silky pocket mouse.

Squirrels are generally clever and persistent animals. In residential neighborhoods, they are notorious for eating out of bird feeders, digging in planting pots and flower beds to pull out bulbs which they chew on or to either bury or recover seeds and nuts and for inhabiting sheltered areas including attics and basements. Squirrels use their keen sense of smell to locate buried nuts and can dig extensive holes in the process. Birds, especially crows, will watch a squirrel bury a nut and will dig it up as soon as the squirrel leaves. Although expert climbers, and primarily arboreal, squirrels also thrive in urban environments.

Squirrels are sometimes considered pests because of their propensity to chew on various edible and inedible objects. This characteristic trait aids in maintaining sharp teeth, and because their teeth grow continuously, prevents over-growth. Homeowners in areas with a heavy squirrel population must keep attics and basements carefully sealed to prevent property damage caused by nesting squirrels. A squirrel nest is called a "drey". Some homeowners resort to more interesting ways of dealing with this problem, such as collecting and planting fur from pets such as domestic cats and dogs in attics. This fur will indicate to nesting squirrels that a potential predator roams and will encourage evacuation. Fake owls and scarecrows are generally ignored by the animals, and the best way to prevent chewing on an object is to coat it with something to make it undesirable: for instance a soft cloth or chili pepper paste or powder.

Squirrel trapping is also practised to remove them from residential areas. However, otherwise squirrels are safe neighbors that pose almost zero risk of transmitting rabies.

Squirrels can be trained to be hand-fed. Because they are able to cache surplus food, they will take as much food as is available. Squirrels living in parks and campuses in cities have learned that humans are typically a ready source of food. Squirrels are occasionally kept as household pets, provided they are selected young enough and are hand raised in a proper fashion. They can be taught to do tricks, and are said to be as intelligent as dogs in their ability to learn behaviors. In these cases, a large cage and a balanced diet with good variety will keep a pet squirrel healthy and happy. As a pet, the owner must be aware of "spring fever" at which time a female pet squirrel will become very defensive of her cage, thinking of it as her nest, and will become somewhat aggressive to defend the area. Pet squirrels are usually kept without cages.

Squirrels are often the cause of power outages. They can readily climb a power pole and crawl across a power line. The animals will climb onto transformers or capacitors looking for food. If they touch a high voltage conductor and a grounded portion of the device at the same time, they are then electrocuted and cause a short circuit that shuts down equipment. Squirrels have brought down the high-tech NASDAQ stock market twice and were responsible for a spate of power outages at the University of Alabama. To sharpen their teeth they will often chew on tree branches or even the occasional live power line. Rubber plates (squirrel guards) are sometimes used to prevent access to these facilities.

Squirrels are blamed for economic losses to homeowners, nut growers, forest managers in addition to damage to electric transmission lines. These losses include direct damage to property, repairs, lost revenue and public relations. While dollar costs of these losses are sometimes calculated for isolated incidents, there is no tracking system to determine the total extent of the losses.

Squirrels are also responsible for burrowing into sensitive earthworks such as dams and levees, causing a loss of structural integrity which requires diligent maintenance and prevention. Squirrel burrowing activity has sometimes resulted in catastrophic failures of these structures.

Urban squirrels have learned to get a great deal of food from over-generous humans. One of the more common and inexpensive foods fed to squirrels is peanuts. Recent studies however have shown that raw peanuts contain a trypsin inhibitor that prevents the absorption of protein in the intestines, therefore offering peanuts that have been roasted is the better option.

However, wildlife rehabilitators in the field have noted that neither raw and roasted peanuts or sunflower seeds are good for squirrels, since they are deficient in several essential nutrients. This type of deficiency has been found to cause Metabolic Bone Disease, a somewhat common ailment found in malnourished squirrels.

Squirrel meat is considered a favored meat in certain regions of the United States where it can be listed as wild game. This is evidenced by extensive recipes for its preparation found in cookbooks, including older copies of The Joy of Cooking. Squirrel meat can be exchanged for rabbit or chicken in recipes, though it can have a gamey taste. Unlike the healthfulness of most game meat, the American Heart Association has found squirrels to be high in cholesterol.

The Albino Squirrel Preservation Society was founded at the University of Texas at Austin in 2001, and its sister chapter at University of North Texas (UNT) petitioned for an election to name their albino squirrel as the university's secondary mascot. The student body narrowly rejected the call. University of Louisville in Kentucky also has a documented population of albino squirrels.

Olney, Illinois, known as the "White Squirrel Capital of the World," is home of the world's largest known albino-squirrel colony. Kenton, Tennessee is home to about 200 albino squirrels.

There are also albino squirrels on the main campus of Ohio State University in Columbus, Ohio. Brevard, North Carolina and Marionville, Missouri have a substantial population of white (not albino) squirrels. Western Kentucky University has a locally famous population of white squirrels. Exeter, Ontario in Canada is known for having non-albino white squirrels, believed to be the result of a genetic mutation in the early 20th century. Black Squirrels with white tips on their tails are being noticed throughout Toronto, Ontario. White squirrels are also commonly seen in Dayton, Ohio and on the campus of Youngstown State University in Youngstown, Ohio. The snow belt in Western and Central New York (Buffalo, Rochester, and Syracuse) also has a significant white squirrel population.

Tiger

2009-06-14T09:21:00.000-07:00

The tiger (Panthera tigris) is a member of the Felidae family; the largest of the four "big cats" in the genus Panthera. Native to much of eastern and southern Asia, the tiger is an apex predator and an obligate carnivore.

Reaching up to 4 metres (13 ft) in total length and weighing up to 300 kilograms (660 pounds), the larger tiger subspecies are comparable in size to the biggest extinct felids. Aside from their great bulk and power, their most recognizable feature is the pattern of dark vertical stripes that overlays near-white to reddish-orange fur, with lighter underparts. The largest subspecies of tiger is the Siberian tiger.

Highly adaptable, tigers range from the Siberian taiga, to open grasslands, to tropical mangrove swamps. They are territorial and generally solitary animals, often requiring large contiguous areas of habitat that support their prey demands. This, coupled with the fact that they are endemic to some of the more densely populated places on earth, has caused significant conflicts with humans. Of the nine subspecies of modern tiger, three are extinct and the remaining six are classified as endangered, some critically so. The primary direct causes are habitat destruction and fragmentation, and hunting. Their historical range, which once reached from Mesopotamia and the Caucasus through most of South and East Asia, has been radically reduced. While all surviving species are under formal protection, poaching, habitat destruction and inbreeding depression continue to be threats.

Nonetheless, tigers are among the most recognizable and popular of the world's charismatic megafauna. They have featured prominently in ancient mythology and folklore, and continue to be depicted in modern films and literature.

Tigers appear on many flags and coats of arms, as mascots for sporting teams, and as the national animal of several Asian nations. The word "tiger" is taken from the Greek word "tigris", which is possibly derived from a Persian source meaning "arrow", a reference to the animal's speed and also the origin for the name of the River Tigris. In American English, "Tigress" was first recorded in 1611. It was one of the many species originally described, as Felis tigris, by Linnaeus in his 18th century work, Systema Naturae. The generic component of its scientific designation, Panthera tigris, is often presumed to derive from Greek pan- ("all") and theron ("beast"), but this may be a folk etymology. Although it came into English through the classical languages, panthera is probably of East Asian origin, meaning "the yellowish animal," or "whitish-yellow".

A group of tigers is rare, but when seen together is termed a 'streak' or an 'ambush'.

In the historical past, tigers were widespread in Asia, from the Caucasus and the Caspian Sea, to Siberia and Indonesia. During the 19th century the striped cats completely vanished from western Asia, and became restricted to isolated pockets in the remaining parts of their range. Today, this fragmented relic range extends from India in the west to China and Southeast Asia in the east. The northern limit is close to the Amur River in south eastern Siberia. The only large island inhabited by tigers today is Sumatra. Tigers vanished from Java and Bali during the 20th century, and in Borneo are known only from fossil remains.

The oldest remains of a tiger-like cat, called Panthera palaeosinensis, have been found in China and Java. This species lived about 2 million years ago, at the beginning of the Pleistocene, and was smaller than a modern tiger.

The earliest fossils of true tigers are known from Java, and are between 1.6 and 1.8 million years old. Distinct fossils from the early and middle Pleistocene were also discovered in deposits from China, and Sumatra. A subspecies called the Trinil tiger (Panthera tigris trinilensis) lived about 1.2 million years ago and is known fossils found at Trinil in Java.

Tigers first reached India and northern Asia in the late Pleistocene, reaching eastern Beringia (but not the American Continent), Japan, and Sakhalin. Fossils found in Japan indicate that the local tigers were, like the surviving island subspecies, smaller than the mainland forms. This may be due to the phenomenon in which body size is related to environmental space (see insular dwarfism), or perhaps the availability of prey. Until the Holocene, tigers also lived in Borneo, as well as on the island of Palawan in the Philippines.

Tigers are perhaps the most recognisable of all the cats (with the possible exception of the lion). They typically have rusty-reddish to brown-rusty coats, a whitish medial and ventral area, a white "fringe" that surrounds the face, and stripes that vary from brown or gray to pure black. The form and density of stripes differs between subspecies (as well as the ground coloration of the fur; for instance, Siberian tigers are usually paler than other tiger subspecies), but most tigers have over 100 stripes. The pattern of stripes is unique to each animal, and thus could potentially be used to identify individuals, much in the same way as fingerprints are used to identify people. This is not, however, a preferred method of identification, due to the difficulty of recording the stripe pattern of a wild tiger. It seems likely that the function of stripes is camouflage, serving to help tigers conceal themselves amongst the dappled shadows and long grass of their environment as they stalk their prey. The stripe pattern is found on a tiger's skin and if shaved, its distinctive camouflage pattern would be preserved. Like other big cats, tigers have a white spot on the backs of their ears.

Tigers have the additional distinction of being the heaviest cats found in the wild. They also have powerfully built legs and shoulders, with the result that they, like lions, have the ability to pull down prey substantially heavier than themselves. However, the subspecies differ markedly in size, tending to increase proportionally with latitude, as predicted by Bergmann's Rule. Thus, large male Siberian Tigers (Panthera tigris altaica) can reach a total length of 3.5 m "over curves" (3.3 m. "between pegs") and a weight of 306 kilograms, which is considerably larger than the sizes reached by island-dwelling tigers such as the Sumatran, the smallest living subspecies with a body weight of only 75-140 kg. Tigresses are smaller than the males in each subspecies, although the size difference between male and female tigers tends to be more pronounced in the larger subspecies of tiger, with males weighing up to 1.7 times as much as the females. In addition, male tigers have wider forepaw pads than females.

This difference is often used by biologists in determining the gender of tigers when observing their tracks. The skull of the tiger is very similar to that of the lion, though the frontal region is usually not as depressed or flattened, with a slightly longer postorbital region. The lion's skull has broader nasal openings. However, due to the amount of skull variation in the two species, usually, only the structure of the lower jaw can be used as a reliable indicator of species.

There are eight recent subspecies of tiger, two of which are extinct. Their historical range (severely diminished today) ran through Bangladesh, Siberia, Iran, Afghanistan, India, China, and southeast Asia, including some Indonesian islands. The surviving subspecies, in descending order of wild population, are:

The Bengal tiger or the Royal Bengal tiger (Panthera tigris tigris) is found in parts of India, Bangladesh, Nepal, Bhutan, and Burma. It lives in varied habitats: grasslands, subtropical and tropical rainforests, scrub forests, wet and dry deciduous forests, and mangroves. Males in the wild usually weigh 205 to 227 kg (450–500 lb), while the average female will weigh about 141 kg. However, the northern Indian and the Nepalese Bengal tigers are somewhat bulkier than those found in the south of the Indian Subcontinent, with males averaging around 235 kilograms (520 lb).

While conservationists already believed the population to be below 2,000, the most recent audit by the Indian Government's National Tiger Conservation Authority has estimated the number at just 1,411 wild tigers (1165–1657 allowing for statistical error), a drop of 60% in the past decade. Since 1972, there has been a massive wildlife conservation project, known as Project Tiger, to protect the Bengal tiger. The project is considered as one of the most successful wildlife conservation programs, though at least one Tiger Reserve (Sariska Tiger Reserve) has lost its entire tiger population to poaching.

The Indochinese tiger (Panthera tigris corbetti), also called Corbett's tiger, is found in Cambodia, China, Laos, Burma, Thailand, and Vietnam. These tigers are smaller and darker than Bengal tigers: Males weigh from 150–190 kg (330–420 lb) while females are smaller at 110–140 kg (242–308 lb). Their preferred habitat is forests in mountainous or hilly regions. Estimates of the Indochinese tiger population vary between 1,200 to 1,800, with only several hundred left in the wild. All existing populations are at extreme risk from poaching, prey depletion as a result of poaching of primary prey species such as deer and wild pigs, habitat fragmentation and inbreeding. In Vietnam, almost three-quarters of the tigers killed provide stock for Chinese pharmacies.

The Malayan tiger (Panthera tigris jacksoni), exclusively found in the southern part of the Malay Peninsula, was not considered a subspecies in its own right until 2004. The new classification came about after a study by Luo et al. from the Laboratory of Genomic Diversity Study, part of the National Cancer Institute of the United States. Recent counts showed there are 600–800 tigers in the wild, making it the third largest tiger population, behind the Bengal tiger and the Indochinese tiger. The Malayan tiger is the smallest of the mainland tiger subspecies, and the second smallest living subspecies, with males averaging about 120 kg and females about 100 kg in weight. The Malayan tiger is a national icon in Malaysia, appearing on its coat of arms and in logos of Malaysian institutions, such as Maybank.

The Sumatran tiger (Panthera tigris sumatrae) is found only on the Indonesian island of Sumatra, and is critically endangered. It is the smallest of all living tiger subspecies, with adult males weighing between 100–140 kg (220–308 lb) and females 75–110 kg (154–242 lb). Their small size is an adaptation to the thick, dense forests of the island of Sumatra where they reside, as well as the smaller-sized prey. The wild population is estimated at between 400 and 500, seen chiefly in the island's national parks. Recent genetic testing has revealed the presence of unique genetic markers, indicating that it may develop into a separate species, if it does not go extinct. This has led to suggestions that Sumatran tigers should have greater priority for conservation than any other subspecies. While habitat destruction is the main threat to existing tiger population (logging continues even in the supposedly protected national parks), 66 tigers were recorded as being shot and killed between 1998 and 2000, or nearly 20% of the total population.

The Siberian tiger (Panthera tigris altaica), also known as the Amur, Manchurian, Altaic, Korean or North China tiger, is confined to the Amur-Ussuri region of Primorsky Krai and Khabarovsk Krai in far eastern Siberia, where it is now protected. Considered the largest subspecies, with a head and body length of 190–230 cm (the tail of a tiger is 60–110 cm long) and an average weight of around 227 kilograms (500 lb) for males, the Amur tiger is also noted for its thick coat, distinguished by a paler golden hue and fewer stripes. The heaviest wild Siberian tiger on record weighed in at 384 kg, but according to Mazak these giants are not confirmed via reliable references. Even so, a six-month old Siberian tiger can be as big as a fully grown leopard. The last two censuses (1996 and 2005) found 450–500 Amur tigers within their single, and more or less continuous, range making it one of the largest undivided tiger populations in the world. Genetic research in 2009 demonstrated that the Siberian tiger, and the western "Caspian tiger" (once thought to have been a separate subspecies that became extinct in the wild in the late 1950s) are actually the same subspecies, since the separation of the two populations may have occurred as recently as the past century due to human intervention.

The South China tiger (Panthera tigris amoyensis), also known as the Amoy or Xiamen tiger, is the most critically endangered subspecies of tiger and is listed as one of the 10 most endangered animals in the world. One of the smaller tiger subspecies, the length of the South China tiger ranges from 2.2–2.6 m (87–100 in) for both males and females. Males weigh between 127 and 177 kg (280–390 lb) while females weigh between 100 and 118 kg (220–260 lb). From 1983 to 2007, no South China tigers were sighted. In 2007 a farmer spotted a tiger and handed in photographs to the authorities as proof. The photographs in question, however, were later exposed as fake, copied from a Chinese calendar and photoshopped, and the “sighting” turned into a massive scandal.

In 1977, the Chinese government passed a law banning the killing of wild tigers, but this may have been too late to save the subspecies, since it is possibly already extinct in the wild. There are currently 59 known captive South China tigers, all within China, but these are known to be descended from only six animals. Thus, the genetic diversity required to maintain the subspecies may no longer exist. Currently, there are breeding efforts to reintroduce these tigers to the wild.

The Balinese tiger (Panthera tigris balica) was limited to the island of Bali. They were the smallest of all tiger subspecies, with a weight of 90–100 kg in males and 65–80 kg in females. These tigers were hunted to extinction—the last Balinese tiger is thought to have been killed at Sumbar Kima, West Bali on 27 September 1937; this was an adult female. No Balinese tiger was ever held in captivity. The tiger still plays an important role in Balinese Hinduism.

The Javan tiger (Panthera tigris sondaica) was limited to the Indonesian island of Java. It now seems likely that this subspecies became extinct in the 1980s, as a result of hunting and habitat destruction, but the extinction of this subspecies was extremely probable from the 1950s onwards (when it is thought that fewer than 25 tigers remained in the wild). The last confirmed specimen was sighted in 1979, but there were a few reported sightings during the 1990s. With a weight of 100-141 kg for males and 75-115 kg for females, the Javan tiger was one of the smaller subspecies, approximately the same size as the Sumatran tiger.

Hybridization among the big cats, including the tiger, was first conceptualized in the 19th century, when zoos were particularly interested in the pursuit of finding oddities to display for financial gain. Lions have been known to breed with tigers (most often the Amur and Bengal subspecies) to create hybrids called ligers and tigons.

Such hybrids were once commonly bred in zoos, but this is now discouraged due to the emphasis on conserving species and subspecies. Hybrids are still bred in private menageries and in zoos in China.

The liger is a cross between a male lion and a tigress. Because the lion sire passes on a growth-promoting gene, but the corresponding growth-inhibiting gene from the female tiger is absent, ligers grow far larger than either parent. They share physical and behavioural qualities of both parent species (spots and stripes on a sandy background). Male ligers are sterile, but female ligers are often fertile. Males have about a 50% chance of having a mane, but, even if they do, their manes will be only around half the size of that of a pure lion. Ligers are typically between 10 to 12 feet in length, and can be between 800 and 1,000 pounds or more.

The less common tigon is a cross between the lioness and the male tiger.

There is a well-known mutation that produces the white tiger, technically known as chinchilla albinistic, an animal which is rare in the wild, but widely bred in zoos due to its popularity. Breeding of white tigers will often lead to inbreeding (as the trait is recessive). Many initiatives have taken place in white and orange tiger mating in an attempt to remedy the issue, often mixing subspecies in the process. Such inbreeding has led to white tigers having a greater likelihood of being born with physical defects, such as cleft palates and scoliosis (curvature of the spine).

Furthermore, white tigers are prone to having crossed eyes (a condition known as strabismus). Even apparently healthy white tigers generally do not live as long as their orange counterparts.

Recordings of white tigers were first made in the early 19th century. They can only occur when both parents carry the rare gene found in white tigers; this gene has been calculated to occur in only one in every 10,000 births. The white tiger is not a separate sub-species, but only a colour variation; since the only white tigers that have been observed in the wild have been Bengal tigers (and all white tigers in captivity are at least part Bengal), it is commonly thought that the recessive gene that causes the white colouring is probably carried only by Bengal tigers, although the reasons for this are not known. Nor are they in any way more endangered than tigers are generally, this being a common misconception. Another misconception is that white tigers are albinos, despite the fact that pigment is evident in the white tiger's stripes. They are distinct not only because of their white hue; they also have blue eyes and pink noses.

In addition, another recessive gene may create a very unusual "golden tabby" colour variation, sometimes known as "strawberry". Golden tabby tigers have light gold fur, pale legs and faint orange stripes. Their fur tends to be much thicker than normal. There are extremely few golden tabby tigers in captivity, around 30 in all. Like white tigers, strawberry tigers are invariably at least part Bengal. Both white and golden tabby tigers tend to be larger than average Bengal tigers.

There are also unconfirmed reports of a "blue" or slate-coloured tiger, the Maltese Tiger, and largely or totally black tigers, and these are assumed, if real, to be intermittent mutations rather than distinct species.

Tigers are essentially solitary and territorial animals. The size of a tiger's home range mainly depends on prey abundance, and, in the case of male tigers, on access to females. A tigress may have a territory of 20 square kilometres while the territories of males are much larger, covering 60–100 km2. The ranges of males tend to overlap those of several females.

The relationships between individuals can be quite complex, and it appears that there is no set "rule" that tigers follow with regards to territorial rights and infringing territories. For instance, although for the most part tigers avoid each other, both male and female tigers have been documented sharing kills. For instance, George Schaller observed a male tiger share a kill with two females and four cubs. Females are often reluctant to let males near their cubs, but Schaller saw that these females made no effort to protect or keep their cubs from the male, suggesting that the male might have been the father of the cubs. In contrast to male lions, male tigers will allow the females and cubs to feed on the kill first. Furthermore, tigers seem to behave relatively amicably when sharing kills, in contrast to lions, which tend to squabble and fight. Unrelated tigers have also been observed feeding on prey together. The following quotation is from Stephen Mills' book Tiger, as he describes an event witnessed by Valmik Thapar and Fateh Singh Rathore in Ranthambhore.

A dominant tigress they called Padmini killed a 250 kg (550-lb) male nilgai - a very large antelope. They found her at the kill just after dawn with her three 14-month-old cubs and they watched uninterrupted for the next ten hours.

During this period the family was joined by two adult females and one adult male - all offspring from Padmini's previous litters and by two unrelated tigers, one female the other unidentified. By three o'clock there were no fewer than nine tigers round the kill.

When young female tigers first establish a territory, they tend to do so fairly close to their mother's area. The overlap between the female and her mother's territory tends to wane with increasing time. Males, however, wander further than their female counterparts, and set out at a younger age to eke out their own area. A young male will acquire territory either by seeking out a range devoid of other male tigers, or by living as a transient in another male's territory, until he is old and strong enough to challenge the resident male. The highest mortality rate (30-35% per year) amongst adult tigers occurs for young male tigers who have just left their natal area, seeking out territories of their own.

Male tigers are generally more intolerant of other males within their territory than females are of other females.

For the most part, however, territorial disputes are usually solved by displays of intimidation, rather than outright aggression. Several such incidents have been observed, in which the subordinate tiger yielded defeat by rolling onto its back, showing its belly in a submissive posture. Once dominance has been established, a male may actually tolerate a subordinate within his range, as long as they do not live in too close quarters. The most violent disputes tend to occur between two males when a female is in oestrus, and may result in the death of one of the males, although this is actually a relatively rare occurrence.

To identify his territory, the male marks trees by spraying of urine and anal gland secretions, as well as marking trails with scat. Males show a grimacing face, called the Flehmen response, when identifying a female's reproductive condition by sniffing their urine markings.

Tigers have been studied in the wild using a variety of techniques. The populations of tigers were estimated in the past using plaster casts of their pugmarks. This method was found faulty and attempts were made to use camera trapping instead.

Newer techniques based on DNA from their scat are also being evaluated. Radio collaring has also been a popular approach to tracking them for study in the wild.

The Association of Zoos and Aquariums estimates that up to 12,000 tigers are being kept as private pets in the USA, significantly more than the world's entire wild population. 4,000 are believed to be in captivity in Texas alone.

Part of the reason for America's enormous tiger population relates to legislation. Only nineteen states have banned private ownership of tigers, fifteen require only a licence, and sixteen states have no regulations at all.

The success of breeding programmes at American zoos and circuses led to an overabundance of cubs in the 1980s and 1990s, which drove down prices for the animals. The SPCA estimate there are now 500 lions, tigers and other big
cats in private ownership just in the Houston area.

In a poll conducted by Animal Planet, the tiger was voted the world's favourite animal, narrowly beating the dog. More than 50,000 viewers from 73 countries voted in the poll. Tigers received 21% of the vote, dogs 20%, dolphins 13%, horses 10%, lions 9%, snakes 8%, followed by elephants, chimpanzees, orangutang.

Lobster

2009-06-12T21:30:00.000-07:00

Clawed lobsters compose a family (Nephropidae, sometimes also Homaridae) of large marine crustaceans. Lobsters are economically important as seafood, forming the basis of a global industry that nets US$13.8 billion in trade annually.

Though several different groups of crustaceans are known as "lobsters," the clawed lobsters are most often associated with the name. Clawed lobsters are not closely related to spiny lobsters or slipper lobsters, which have no claws (chelae), or squat lobsters. The closest relatives of clawed lobsters are the reef lobster Enoplometopus and the three families of freshwater crayfish.

Lobsters are invertebrates and are found all over the world. They have a hard protective exoskeleton. Like most arthropods, lobsters must molt in order to grow, leaving them vulnerable during this time. During the molting process, several species may experience a change in color. Lobsters have 10 legs, with the front ones adapted to claws.

Lobsters live on rocky, sandy, or muddy bottoms from the shoreline to beyond the edge of the continental shelf. They generally live singly in crevices or in burrows under rocks.

Lobsters typically eat live food, consisting of fish, mollusks, other crustaceans, worms, and some plant life. Occasionally, they will scavenge if necessary, and may resort to cannibalism in captivity; however, this has not been observed in the wild. Although lobster skin has been found in the stomachs of lobsters, this is because lobsters will eat their shed skin after molting. Lobsters grow throughout their lives and it is not unusual for a lobster to live for more than 100 years. In fact, lobsters may exhibit "negligible senescence", in that they can effectively live indefinitely, barring injury, disease, capture, etc. They can thus reach impressive sizes.

According to the Guinness World Records, the largest lobster was caught in Nova Scotia, Canada, and weighed 20.15 kg (44.4 lb).

Although clawed lobsters, like most other arthropods, are largely bilaterally symmetrical, they often possess unequal, specialized claws, like the king crab. A freshly caught lobster will have a claw which is full and fleshy, not atrophied. The anatomy of the lobster includes the cephalothorax which is the head fused with the thorax, both of which are covered by the carapace, of chitinous composition, and the abdomen. The lobster's head consists of antennae, antennules, mandibles, the first and second maxillae, and the first, second, and third maxillipeds.

Because a lobster lives in a murky environment at the bottom of the ocean, its vision is poor and it mostly uses its antennae as sensors. Studies have shown that the lobster eye is formed with a reflective structure atop a convex retina. In contrast, most complex eyes use refractive ray concentrators (lenses) and a concave retina. The abdomen of the lobster includes swimmerets and its tail is composed of uropods and the telson.

Lobsters, like snails and spiders, have blue blood due to the presence of haemocyanin, which contains copper. (In contrast, mammals and many other animals, have red blood due to the presence of haemoglobin, which contains iron.)

Inside lobsters is a green goopy substance called tomalley, which serves as the hepatopancreas, fulfilling the functions of both liver and pancreas.

In general, lobsters are 25 cm to 50 cm long ( 10 to 20 inches ) and move slowly by walking on the bottom of the sea floor. However, when they flee, they swim backwards quickly by curling and uncurling their abdomen. A speed of five meters per second (about 11 mph) has been recorded. This is known as the caridoid escape reaction.

Lobster recipes include Lobster Newberg and Lobster Thermidor. Lobsters are sold with claws banded to prevent them from injuring each other or people. Lobsters cannot open claws when banded, which causes the claws to atrophy. Recently banded lobsters will not show this, and the claws will be full.

Lobsters may be prepared and cooked while alive (removing claws may not kill lobsters). Cooks place the live lobster in boiling water or steam. Lobsters are also served fried, grilled, or baked. Freezing the lobster may toughen the meat. A common misconception is that a lobster screams when boiled; this is due to steam escaping the shell, creating a whistling.

When boiling, the lobster is simmered for seven minutes for the first pound and three minutes for each additional pound.

The majority of the meat is in the tail and the two front claws, but smaller quantities are in the legs and torso. Lobster is used variously, for example in soup, bisque or lobster rolls. Lobster meat is maybe dipped in clarified butter, resulting in a sweetened flavor. As with all shellfish, lobster is not kosher.

The European wild lobster, including the royal blue lobster of Audresselles, is more expensive and rare than the American lobster. It was consumed chiefly by the royal and aristocratic families of France and the Netherlands.

Such scenes were depicted in Dutch paintings of the sixteenth and seventeenth centuries.

In North America, the American lobster did not become a popular food until the mid-19th century, when New Yorkers and Bostonians developed a taste; not until the invention of a special vessel, the lobster smack, did a commercial fishery flourish. Prior to this time, eating lobster was considered a mark of poverty or as a food for indentured servants or lower members of society in Maine, Massachusetts and the Canadian Maritimes. Prior to the American Revolutionary War, dock workers in Boston went on strike, protesting having to eat lobster more than three times a week. Lobsters were used as a fertilizer for farms. In Canada, outside of the rural outposts lobster was sold canned; New England's fresh lobster trade extended to Philadelphia.

The market for lobster changed with the transportation industry allowing live lobsters to be shipped from the ports to urban centres. Fresh lobster became a luxury food and a tourist attraction for the Maritime provinces and an export to Europe and Japan where it is especially expensive.

The high price of lobster led to creating "faux lobster". It is often made from pollock or other whitefish altered to look and taste similar to lobster. A few restaurants sell "langostino lobster". Langostino translates into prawn; the actual animal may be crab. The spiny lobster is also called langouste.

Lobsters are caught using baited, one-way traps with a color-coded marker buoy to mark cages. Lobster is fished in water between 1 and 500 fathoms, although some lobsters live at 2,000 fathoms. Cages are of plastic-coated galvanized steel or wood. A lobster fisher may tend between 10 and 2,000 traps. Around the year 2000, due to overfishing of some species and high demand lobster farming became more prevalent. As of 2008, no lobster farming operation has achieved commercial success.

Due to the ambiguous nature of suffering, the issue of lobster pain may be approached using an argument by analogy — that lobsters are similar to human biology or that behavior warrants assumptions that lobsters can feel pain.

The Norwegian Scientific Committee for Food Safety tentatively concluded that "it is unlikely that [lobsters] can feel pain," though they note that "there is apparently a paucity of exact knowledge on sentience in crustaceans, and more research is needed." This conclusion is based on the lobster's simple nervous system. The report assumes that the violent reaction of lobsters to boiling water is a reflex to noxious stimuli.

However, review by the Scottish animal rights group Advocate for Animals released in the same year reported that "scientific evidence ... strongly suggests that there is a potential for [lobsters] to experience pain and suffering," primarily because lobsters (and other decapod crustaceans) "have opioid receptors and respond to opioids (analgesics such as morphine) in a similar way to vertebrates," indicating that lobsters' reaction to injury changes when painkillers are applied. The similarities in lobsters' and vertebrates' stress systems and behavioral responses to noxious stimuli were given as additional evidence for their capacity for pain.

A 2007 study at Queen's University, Belfast, suggested that crustaceans do feel pain. In the experiment, when the antennae of prawns were rubbed with sodium hydroxide or acetic acid, the animals showed increased grooming of the afflicted area and rubbed it more against the side of the tank. Moreover, this reaction was inhibited by a local anesthetic, even though control prawns treated with only anesthetic did not show reduced activity. Professor Robert Elwood, who headed the study, argues that sensing pain is crucial to prawn survival, because it encourages them to avoid damaging behaviors. Some scientists responded, saying the rubbing may reflect an attempt to clean the affected area.

In a subsequent 2009 study, Prof. Elwood and Mirjam Appel showed that hermit crabs make motivational tradeoffs between shocks and the quality of the shells they inhabit. In particular, as crabs are shocked more intensely, they become increasingly willing to leave their current shells for new shells, and they spend less time deciding whether to enter those new shells. Moreover, because the researchers did not offer the new shells until after the electrical stimulation had ended, the change in motivational behavior was the result of memory of the noxious event, not an immediate reflex.

In vertebrates, endogenous opioids are neurochemicals that moderate pain by interacting with opiate receptors. Opioid peptides and opiate receptors occur naturally in crustaceans, and although “at present no certain conclusion
can be drawn,” some have interpreted their presence as an indication that lobsters may be able to experience pain.

The aforementioned Scottish paper holds that lobsters' opioids may "mediate pain in the same way" as in vertebrates.

Morphine, an analgesic, and naloxone, an opioid receptor antagonist, may affect a related species of crustacean (Chasmagnathus granulatus) in much the same way they affect vertebrates: injections of morphine into crabs produced a dose-dependent reduction of their defensive response to an electric shock. (However, the attenuated defensive response could originate from either the analgesic or sedative properties of morphine, or both). These findings have been replicated for other invertebrate species, but similar data is not yet available for lobsters.

The most common way of killing a lobster is by placing it, live, in boiling water, or by splitting: severing the body in half, lengthwise.

The boiling method (also used to kill crabs, crayfish and shrimp) is controversial because some believe that the lobster suffers. The practice is illegal in some places, such as in Reggio Emilia, Italy, where offenders face fines of up to €495. The Norwegian study states that the lobster may be de-sensitized by placing it in a salt solution 15 minutes before killing it.

In 2006, British inventor Simon Buckhaven invented the CrustaStun, which electrocutes lobsters with a 110 V electric shock, killing them in five seconds. This ensures a quicker death for the lobster. Seafood wholesalers in Britain use a commercial version. A home version was available about 2006.

Koala

2009-06-12T11:25:00.000-07:00

The Koala (Phascolarctos cinereus) is a thickset arboreal marsupial herbivore native to Australia, and the only extant representative of the family Phascolarctidae.

The koala is found in coastal regions of eastern and southern Australia, from near Adelaide to the southern part of Cape York Peninsula. Populations also extend for considerable distances inland in regions with enough moisture to support suitable woodlands. The koalas of South Australia were largely exterminated during the early part of the 20th century, but the state has since been repopulated with Victorian stock. The koala is not found in Tasmania or Western Australia.

The word koala comes from the Dharuk gula. Although the vowel /u/ was originally written in the Latin alphabet as "oo" (in spellings such as coola or koolah), it was changed to "oa" possibly due to an error. The word is erroneously said to mean "doesn't drink".

The scientific name of the koala's genus, Phascolarctos, is derived from Greek phaskolos "pouch" and arktos "bear". Its species name, cinereus, is Latin and means "ash-coloured".

Although the koala is not a bear, when first adopted by English speakers, the name koala bear became popular, as this roughly evoked the species' similarity in appearance to the Teddy bear, to people unfamiliar with it. Although taxonomically incorrect, the name koala bear is still in use today outside Australia — its use is discouraged because of the inaccuracy in the name. Other descriptive English names based on "bear" have included monkey bear, native bear, and tree-bear.

Although three subspecies have been described, these are arbitrary selections from a cline and are not generally accepted as valid. Following Bergmann's Rule, southern individuals from the cooler climates are larger. A typical Victorian koala (formerly P. cinereus victor) has longer, thicker fur, is a darker, softer grey, often with chocolate-brown highlights on the back and forearms, and has a more prominently light-coloured ventral side and fluffy white ear tufts. Typical and New South Wales koala weights are 12 kg (26 lb) for males and 8.5 kg (19 lb) for females. In tropical and sub-tropical Queensland, however, the koala is smaller (at around 6.5 kg (14 lb) for an average male and just over 5 kg (11 lb) for an average female), a lighter often rather scruffy grey in colour, and has shorter, thinner fur. In Queensland, the koala was previously classified as the subspecies P. cinereus adustus, and the intermediate forms in New South Wales as P. cinereus cinereus. The variation from one form to another is continuous and there are substantial differences between individual koalas in any given region such as hair colour.

The origins of the koala are unclear, although almost certainly they descended from terrestrial wombat-like animals. Koala fossils are quite rare, but some have been found in northern Australia dating to 20 million years ago.

During this time, the northern half of Australia was rainforest. The koala did not specialise in a diet of eucalypts until the climate cooled and eucalypt forests grew in the place of rainforests. The fossil record indicates that before 50,000 years ago, giant koalas inhabited the southern regions of Australia. The koala fills the same ecological role as the sloth of South America.

The koala is broadly similar in appearance to the wombat (its closest living relative), but has a thicker coat, much larger ears, and longer limbs. The koala has large, sharp claws to assist with climbing tree trunks. Weight varies from about 14 kg (31 lb) for a large southern male, to about 5 kg (11 lb) for a small northern female. The koala's five fingers are arranged with opposable thumbs, providing better gripping ability. The first two fingers are positioned in apposition on the front paws, and the first three fingers for the hind paws. The koala is one of the few mammals (other than primates) that has fingerprints. Koala fingerprints are similar to human fingerprints; even with an electron microscope, it can be quite difficult to distinguish between the two.

The teeth of the koala are adapted to their herbivorous diet, and are similar to those of other diprotodont marsupials, such as kangaroos and wombats. They have sharp incisors to clip leaves at the front of the mouth, separated from the grinding cheek teeth by a wide diastema.

The male koala, like many marsupials, has a bifurcated penis. The female has two lateral vaginas and two separate uteri, which is common to all marsupials.

The brain in the ancestors of the modern koala once filled the whole cranial cavity, but has become drastically reduced in the present species, a degeneration scientists suspect is an adaptation to a diet low in energy. One of the smallest in marsupials with no more than 0.2% of its body weight, about 40% of the cranial cavity is filled with cerebrospinal fluid, while the brain's two cerebral hemispheres are like "a pair of shrivelled walnut halves on top of the brain stem, in contact neither with each other nor the bones of the skull. It is the only animal on Earth with such a strangely reduced brain."

It is generally a silent animal, but males have a very loud advertising call that can be heard from almost a kilometre away during the breeding season. When under stress, koalas may issue a loud cry, which has been reported as similar to that of a human baby. There is little reliable information about the lifespan of the koala, but in captivity they have been observed to reach the age of 18 years.

Females reach maturity at 2 to 3 years of age, males at 3 to 4 years. A healthy female koala can produce one young each year for about 12 years. Gestation is 35 days. Twins are very rare; the world's first confirmed identical twin koalas, named "Euca" and "Lyptus", were born at the University of Queensland in 1999. Mating normally occurs between December and March, the Southern Hemisphere's summer.

A baby koala is referred to as a joey and is hairless, blind, and earless. At birth the joey, only a quarter of an inch long, crawls into the downward-facing pouch on the mother's belly (which is closed by a drawstring-like muscle that the mother can tighten at will) and attaches itself to one of the two teats.

Young remain hidden in the pouch for about six months, only feeding on milk. During this time they grow ears, eyes, and fur. The joey then begins to explore outside of the pouch. At about this stage it begins to consume small quantities of the mother’s "pap" (formerly thought to be excrement, but now thought to come from the mother's cecum) in order to inoculate its gut with the microbes necessary to digest eucalypt leaves. The joey will remain with its mother for another six months or so, riding on her back, and feeding on both milk and eucalypt leaves until weaning is complete at about 12 months of age. Young females disperse to nearby areas at that time; young males often stay in the mother's home range until they are two or three years old.

The koala lives almost entirely on eucalypt leaves. This is likely to be an evolutionary adaptation that takes advantage of an otherwise unfilled ecological niche, since eucalypt leaves are low in protein, high in indigestible substances, and contain phenolic and terpene compounds that are toxic to most species. Like wombats and sloths, the koala has a very low metabolic rate for a mammal and rests motionless for about 16 to 18 hours a day, sleeping most of that time. Koalas that are disturbed are known to be violent, their teeth and claws capable of causing considerable injury to humans; special handling requirements are as such applicable.

Handling of koalas has been a source of political contention due to these risks, which can cause harm to the koala as well. Koalas spend about three of their five active hours eating. Feeding occurs at any time of day, but usually at night. An average koala eats 500 g (18 oz) of eucalypt leaves each day, chewing them in its powerful jaws to a very fine paste before swallowing. The liver deactivates the toxic components ready for excretion, and the hind gut (especially the caecum) is greatly enlarged to extract the maximum amount of nutrient from the poor quality diet. Much of this is done through bacterial fermentation: while young are being weaned, the mother passes these essential digestive aids on to her offspring.

The koala will eat the leaves of a wide range of eucalypts, and occasionally even some non-eucalypt species such as Acacia, Leptospermum, and Melaleuca. It has firm preferences for particular varieties of eucalypt and these preferences vary from one region to another: in the south Manna Gum, Blue Gum, and Swamp Gum are favoured; Grey Gum and Tallowwood are important in the north, and the ubiquitous River Red Gum of the isolated seasonal swamps and watercourses that meander across the dry inland plains allows the koala to live in surprisingly arid areas. Many factors determine which of the 680 species of eucalypt trees the koala eats.

Among trees of their favourite species, however, the major factor that determines which individual trees the koala chooses is the concentration of a group of phenolic toxins called formylated phloroglucinol compounds.

The Australian Government currently lists the koala as a priority species for conservation status assessment. Government estimates of the national koala population numbers in the hundreds of thousands, although other studies have estimated as few as 80 000 koalas left in the wild.

Aardvark

2009-06-12T10:25:00.000-07:00

The Aardvark (Orycteropus afer) (afer: from Africa) is a medium-sized, burrowing, nocturnal mammal native to Africa. It is sometimes called "antbear", "anteater", "Cape anteater" (after the Cape of Good Hope), "earth hog" or "earth pig". The name comes from the Afrikaans/Dutch for "earth pig" (aarde earth, varken pig), because early settlers from Europe thought it resembled a domesticated pig. However, the aardvark is not closely related to the pig; rather, it is the sole recent representative of the obscure mammalian order Tubulidentata, in which it is usually considered to form a single variable species of the genus Orycteropus, coextensive with the family Orycteropodidae. Nor is the aardvark closely related to the South American anteater, despite sharing some characteristics and a superficial resemblance. The closest living relatives of the aardvark are the elephant shrews, along with the sirenians, hyraxes, tenrecs, and elephants.

One of the most distinctive characteristics of the Tubulidentata is (as the name implies) their teeth. Instead of having a pulp cavity, each tooth has a cluster of thin, upright, parallel tubes of vasodentin (a modified form of dentine), with individual pulp canals, held together by cementum. The teeth have no enamel coating and are worn away and regrow continuously.

The aardvark is born with conventional incisors and canines at the front of the jaw,
which fall out and are not replaced. Adult aardvarks only have cheek teeth at the back of the jaw.

Genetically speaking, the aardvark is a living fossil, as its chromosomes are highly conserved, reflecting much of the early eutherian arrangement before the divergence of the major modern taxa.

The aardvark is vaguely pig-like in appearance. Its body is stout with an arched back and is sparsely covered with coarse hairs. The limbs are of moderate length. The front feet have lost the pollex (or 'thumb') — resulting in four toes — but the rear feet have all five toes. Each toe bears a large, robust nail which is somewhat flattened and shovel-like, and appears to be intermediate between a claw and a hoof. The ears are disproportionately long, and the tail is very thick at the base and gradually tapers. The greatly elongated head is set on a short, thick neck, and the end of the snout bears a disc, which houses the nostrils. The mouth is small and tubular, typical of species that feed on termites. The aardvark has a long, thin, snakelike, protruding tongue and elaborate structures supporting a keen sense of smell.

An aardvark's weight is typically between 40 and 65 kg. An aardvark's length is usually between 1 and 1.3 meters, and can reach lengths of 2.2 meters when its tail (which can be up to 70 centimeters) is taken into account. The aardvark is pale yellowish gray in color and often stained reddish-brown by soil. The aardvark's coat is thin and the animal's primary protection is its tough skin. The aardvark has been known to sleep in a recently excavated ant nest, which also serves as protection.

The aardvark is nocturnal and is a solitary creature that feeds almost exclusively on ants and termites (formicivore); the only fruit eaten by aardvarks is the aardvark cucumber. An aardvark emerges from its burrow in the late afternoon or shortly after sunset, and forages over a considerable home range encompassing 10 to 30 kilometers, swinging its long nose from side to side to pick up the scent of food. When a concentration of ants or termites is detected, the aardvark digs into it with its powerful front legs, keeping its long ears upright to listen for predators, and takes up an astonishing number of insects with its long, sticky tongue—as many as 50,000 in one night have been recorded. It is an exceptionally fast digger, but otherwise moves fairly slowly. Its claws enable it to dig through the extremely hard crust of a termite or ant mound quickly, avoiding the dust by sealing the nostrils. When successful, the aardvark's long (as long as 30 centimeters) tongue licks up the insects; the termites' biting, or the ants' stinging attacks are rendered futile by the tough skin. Its keen hearing warns it of predators: lions, leopards, hyenas, and pythons.

Aside from digging out ants and termites, the aardvark also excavates burrows in which to live: temporary sites are scattered around the home range as refuges, and a main burrow is used for breeding. Main burrows can be deep and extensive, have several entrances and can be as long as 13 meters. The aardvark changes the layout of its home burrow regularly, and from time to time moves on and makes a new one; the old burrows are then inhabited by smaller animals like the African Wild Dog. Only mothers and young share burrows. If attacked in the tunnel, it will seal the tunnel off behind itself or turn around and attack with its claws.

Click to visit the Aardvark. http://tinyurl.com/lmxbn5

Aardvarks only pair during the breeding season; after a gestation period of 7 months, a single cub weighing around 2 kg is born, and is able to leave the burrow to accompany its mother after only two weeks, and is eating termites at 14 weeks and is weaned by 16 weeks. At six months of age it is able to dig its own burrows, but it will often remain with the mother until the next mating season, and is sexually capable by the season after that.

Aardvarks can live to be over 24 years old in captivity.

The aardvark's main predators are lions, leopards, hunting dogs and pythons. Aardvarks can dig fast or run in zigzag fashion to elude enemies, but if all else fails, they will strike with their claws, tail and shoulders, sometimes flipping onto their backs to lash with all fours. Their thick skin also protects them to some extent.

Aardvarks live in subsaharan Africa, where there is suitable habitat for them to live, such as savannas, grasslands, woodlands and bushland, and available food (i.e., ants and termites).

Click and visit more Aardvarks. http://tinyurl.com/m92by5

In African folklore the aardvark is much admired because of its diligent quest for food and its fearless response to the strong, warlike soldier ant. Hausa magicians make a charm from the heart, skin, forehead, and nails of the aardvark, which they then proceed to pound together with the root of a certain tree. Wrapped in a piece of skin and worn on the chest the charm is said to give the owner the ability to pass through walls or roofs at night. The charm is said to be used by burglars and those seeking to visit young girls without their parents' permission.

In English-speaking countries, the aardvark enjoys unusual notoriety, since it is the first noun, and often the first illustrated entry, in many English dictionaries. The main character of Arthur, a popular animated television series for children produced by WGBH-TV and shown in more than 100 countries, is an aardvark.

Platypus

2009-06-11T15:12:00.000-07:00

The Platypus (Ornithorhynchus anatinus) is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young. It is the sole living representative of its family (Ornithorhynchidae) and genus (Ornithorhynchus), though a number of related species have been found in the fossil record.

The bizarre appearance of this egg-laying, venomous, duck-billed, beaver-tailed, otter-footed mammal baffled European naturalists when they first encountered it, with some considering it an elaborate fraud. It is one of the few venomous mammals; the male Platypus has a spur on the hind foot that delivers a venom capable of causing severe pain to humans. The unique features of the Platypus make it an important subject in the study of evolutionary biology and a recognizable and iconic symbol of Australia; it has appeared as a mascot at national events and is featured on the reverse of the Australian 20 cent coin. The platypus is the animal emblem of the state of New South Wales.

Until the early 20th century it was hunted for its fur, but it is now protected throughout its range. Although captive breeding programs have had only limited success and the Platypus is vulnerable to the effects of pollution, it is not under any immediate threat.

When the Platypus was first discovered by Europeans in 1798, a pelt and sketch were sent back to the United Kingdom by Captain John Hunter, the second Governor of New South Wales. The British scientists were at first convinced that the attributes must have been a hoax. George Shaw, who produced the first description of the animal in the Naturalist's Miscellany in 1799, stated that it was impossible not to entertain doubts as to its genuine nature, and Robert Knox believed it may have been produced by some Asian taxidermist. It was thought that somebody had sewn a duck's beak onto the body of a beaver-like animal. Shaw even took a pair of scissors to the dried skin to check for stitches.

The common name, Platypus, is Latin derived from the Greek words πλατύς ("platys", flat, broad) and πους ("pous", foot), meaning "flat foot". Shaw assigned it as a Linnaean genus name when he initially described it, but the term was quickly discovered to already belong to the wood-boring ambrosia beetle (genus Platypus). It was independently described as Ornithorhynchus paradoxus by Johann Blumenbach in 1800 (from a specimen given to him by Sir Joseph Banks) and following the rules of priority of nomenclature it was later officially recognised as Ornithorhynchus anatinus.

The scientific name Ornithorhynchus is derived from ορνιθόρυνχος ("ornithorhynkhos"), which literally means "bird snout" in Greek, and anatinus, which means "duck-like" in Latin.

There is no universally agreed upon plural of "platypus" in the English language. Scientists generally use "platypuses" or simply "platypus". Colloquially, "platypi" is also used for the plural, although this is pseudo-Latin; the Greek plural would be "platypodes". Early British settlers called it by many names, such as watermole, duckbill, and duckmole. The name "Platypus" is often prefixed with the adjective "duck-billed" to form Duck-billed Platypus, despite there being only one species of Platypus.

The body and the broad, flat tail of the Platypus are covered with dense brown fur that traps a layer of insulating air to keep the animal warm. The Platypus uses its tail for storage of fat reserves (an adaptation also found in animals such as the Tasmanian Devil and fat-tailed sheep). It has webbed feet and a large, rubbery snout; these are features that appear closer to those of a duck than to those of any known mammal. The webbing is more significant on the front feet and is folded back when walking on land. Unlike a bird's beak (in which the upper and lower parts separate to reveal the mouth), the snout of the Platypus is a sensory organ with the mouth on the underside. The nostrils are located on the dorsal surface of the snout, while the eyes and ears are located in a groove set just back from it; this groove is closed when swimming. Platypuses have been heard to emit a low growl when disturbed and a range of other vocalisations have been reported in captive specimens.

Weight varies considerably from 0.7 to 2.4 kg (1.5 to 5.3 lb), with males being larger than females: males average 50 cm (20 in) total length while females average 43 cm (17 in). There is substantial variation in average size from one region to another, and this pattern does not seem to follow any particular climatic rule and may be due to other environmental factors such as predation and human encroachment.

The Platypus has an average body temperature of about 32 °C (90 °F) rather than the 37 °C (99 °F) typical of placental mammals. Research suggests this has been a gradual adaptation to harsh environmental conditions on the part of the small number of surviving monotreme species rather than a historical characteristic of monotremes.

The modern Platypus young have three-cusped molars which they lose before or just after leaving the breeding burrow; adults have heavily keratinised pads in their place. The Platypus jaw is constructed differently from that of other mammals, and the jaw-opening muscle is different. As in all true mammals, the tiny bones that conduct sound in the middle ear are fully incorporated into the skull, rather than lying in the jaw as in cynodonts and other pre-mammalian synapsids. However, the external opening of the ear still lies at the base of the jaw. The Platypus has extra bones in the shoulder girdle, including an interclavicle, which is not found in other mammals. It has a reptilian gait, with legs that are on the sides of the body, rather than underneath.

While both male and female Platypus are born with ankle spurs, only the male has spurs which produce a cocktail of venom, composed largely of defensin-like proteins (DLPs), three of which are unique to the Platypus. The defensin proteins are produced by the immune system of the platypus. Although powerful enough to kill smaller animals such as dogs, the venom is not lethal to humans, but is so excruciating that the victim may be incapacitated. Oedema rapidly develops around the wound and gradually spreads throughout the affected limb.

Information obtained from case histories and anecdotal evidence indicates that the pain develops into a long-lasting hyperalgesia that persists for days or even months. Venom is produced in the crural glands of the male, which are kidney-shaped alveolar glands connected by a thin-walled duct to a calcaneus spur on each hind limb. The female Platypus, in common with echidnas, has rudimentary spur buds which do not develop (dropping off before the end of their first year) and lack functional crural glands.

The venom appears to have a different function from those produced by non-mammalian species: its effects are not life-threatening but nevertheless powerful enough to seriously impair the victim. Since only males produce venom and production rises during the breeding season, it is theorised that it is used as an offensive weapon to assert dominance during this period.

Monotremes (see also echidna for the other species) are the only mammals known to have a sense of electroreception: they locate their prey in part by detecting electric fields generated by muscular contractions. The Platypus' electroreception is the most sensitive of any monotreme.

Click and visit the Platypus. http://tinyurl.com/r5rb3r

The electroreceptors are located in rostro-caudal rows in the skin of the bill, while mechanoreceptors (which detect touch) are uniformly distributed across the bill. The electrosensory area of the cerebral cortex is contained within the tactile somatosensory area, and some cortical cells receive input from both electroreceptors and mechanoreceptors, suggesting a close association between the tactile and electric senses. Both electroreceptors and mechanoreceptors in the bill dominate the somatotopic map of the platypus brain, in the same way human hands dominate the Penfield homunculus map.

The Platypus can determine the direction of an electric source, perhaps by comparing differences in signal strength across the sheet of electroreceptors. This would explain the animal's characteristic side-to-side motion of its head while hunting. The cortical convergence of electrosensory and tactile inputs suggests a mechanism for determining the distance of prey items which, when they move, emit both electrical signals and mechanical pressure pulses, which would also allow for computation of distance from the difference in time of arrival of the two signals.

The Platypus feeds not by sight or smell, closing its eyes, ears and nose each time it dives and digs in the bottom of streams with its bill. The electroreceptors in its bill detect minute movements of its prey to distinguish animate and inanimate objects in which its mechanoreceptors are continuously stimulated. Detecting prey generates tiny electrical currents in its sensitive electroreceptors which the Platypus senses as muscular contractions. Experiments have shown that the Platypus will even react to an "artificial shrimp" if a small electrical current is passed through it.

The Platypus is semi-aquatic, inhabiting small streams and rivers over an extensive range from the cold highlands of Tasmania and the Australian Alps to the tropical rainforests of coastal Queensland as far north as the base of the Cape York Peninsula. Inland, its distribution is not well known: it is extinct in South Australia (barring an introduced population on Kangaroo Island) and is no longer found in the main part of the Murray-Darling Basin, possibly due to the declining water quality brought about by extensive land clearing and irrigation schemes. Along
the coastal river systems, its distribution is unpredictable; it appears to be absent from some relatively healthy rivers, and yet maintains a presence in others that are quite degraded (the lower Maribyrnong, for example).

In captivity, Platypuses have survived to seventeen years of age and wild specimens have been recaptured at eleven years old. Mortality rates for adults in the wild appear to be low. Natural predators include snakes, water rats, goannas, hawks, owls and eagles. Low Platypus numbers in northern Australia are possibly due to predation by crocodiles. The introduction of red foxes as a predator for rabbits may have had some impact on its numbers on the mainland. The Platypus is generally regarded as nocturnal and crepuscular, but individuals are also active during the day, particularly when the sky is overcast. Its habitat bridges rivers and the riparian zone for both a food supply of prey species and banks where it can dig resting and nesting burrows. It may have a range of up to 7 km (4.3 mi), with male's home ranges overlapping with those of 3 or 4 females.

The Platypus is an excellent swimmer and spends much of its time in the water foraging for food. When swimming it can be distinguished from other Australian mammals by the absence of visible ears. Uniquely among mammals it propels itself when swimming by alternate rowing motion with the front two feet; although all four feet of the Platypus are webbed, the hind feet (which are held against the body) do not assist in propulsion, but are used for steering in combination with the tail. The species is endothermic, maintaining its body temperature about 32 °C (90 °F), lower than most mammals, even while foraging for hours in water below 5 °C (41 °F).

Dives normally last around 30 seconds, but can last longer although few exceed the estimated aerobic limit of 40 seconds. 10 to 20 seconds are commonly spent in recovery at the surface. The Platypus is a carnivore: it feeds on annelid worms and insect larvae, freshwater shrimps, and yabbies (freshwater crayfish) that it digs out of the riverbed with its snout or catches while swimming. It utilises cheek-pouches to carry prey to the surface where they are eaten. The Platypus needs to eat about 20% of its own weight each day. This requires the Platypus to spend an average of 12 hours each day looking for food. When not in the water, the Platypus retires to a short, straight resting burrow of oval cross-section, nearly always in the riverbank not far above water level, and often hidden under a protective tangle of roots.

Click to visit more Platypus. http://tinyurl.com/plhraw

When the Platypus was first discovered, scientists were divided over whether the female laid eggs. This was not confirmed until 1884 when W. H. Caldwell was sent to Australia where, after extensive searching assisted by a team of 150 Aborigines, he managed to discover a few eggs. Mindful of the high cost of wiring England based on the cost per word, Caldwell famously but tersely wired London, "Monotremes oviparous, ovum meroblastic". That is, monotremes lay eggs, and the eggs are similar to those of reptiles in that only part of the egg divides as it develops.

The species exhibits a single breeding season; mating occurs between June and October, with some local variation taking place in populations across the extent of its range. Historical observation, mark and recapture studies, and preliminary investigations of population genetics indicate the possibility of resident and transient members of populations and suggest a polygynous mating system. Females are thought likely to become sexually mature in their second year, with breeding confirmed to still take place in animals over nine years old.

Outside the mating season, the Platypus lives in a simple ground burrow whose entrance is about 30 cm (12 in) above the water level. After mating, the female constructs a deeper, more elaborate burrow up to 20 m (66 ft) long and blocked with plugs at intervals (which may act as a safeguard against rising waters or predators, or as a method of regulating humidity and temperature). The male takes no part in caring for its young, and retreats to its yearlong burrow. The female softens the ground in the burrow with dead, folded, wet leaves and she fills the nest at the end of the tunnel with fallen leaves and reeds for bedding material. This material is dragged to the nest by tucking it underneath her curled tail.

The female Platypus has a pair of ovaries but only the left one is functional. It lays one to three (usually two) small, leathery eggs (similar to those of reptiles), that are about 11 mm (0.43 in) in diameter and slightly rounder than bird eggs. The eggs develop in utero for about 28 days with only about 10 days of external incubation (in contrast to a chicken egg, which spends about 1 day in tract and 21 days externally). After laying her eggs, the female curls around them. The incubation period is separated into three parts. In the first, the embryo has no functional organs and relies on the yolk sac for sustenance. The yolk is absorbed by the developing young.
During the second, the digits develop, and in the last, the egg tooth appears.

The newly hatched young are vulnerable, blind, and hairless, and are fed by the mother's milk. Although possessing mammary glands, the Platypus lacks teats. Instead, milk is released through pores in the skin. There are grooves on her abdomen that form pools of milk, allowing the young to lap it up. After they hatch, the offspring are suckled for three to four months.

During incubation and weaning, the mother initially only leaves the burrow for short periods to forage. When doing so, she creates a number of thin soil plugs along the length of burrow possibly to protect the young from predators; pushing past these on her return forces water from her fur and allows the burrow to remain dry. After about five weeks, the mother begins to spend more time away from her young and at around four months the young emerge from the burrow. A platypus is born with teeth, but these drop out at a very early age, leaving the horny plates they grind their food with.

The Platypus and other monotremes were very poorly understood and some of the 19th century myths that grew up around them—for example, that the monotremes were "inferior" or quasi-reptilian—still endure. In 1947, William King Gregory theorised that placental mammals and marsupials may have diverged earlier and a subsequent branching divided the monotremes and marsupials, but later research and fossil discoveries have suggested this is incorrect. In fact, modern monotremes are the survivors of an early branching of the mammal tree, and a later branching is thought to have led to the marsupial and placental groups.

The oldest discovered fossil of the modern Platypus dates back to about 100,000 years ago, during the Quaternary period. The extinct monotremes (Teinolophos and Steropodon) were closely related to the modern Platypus. The fossilised Steropodon was discovered in New South Wales and is composed of an opalised lower jawbone with three molar teeth (whereas the adult contemporary Platypus is toothless). The molar teeth were initially thought to be tribosphenic, which would have supported a variation of Gregory's theory, but later research has suggested that, while they have three cusps, they evolved under a separate process. The fossil is thought to be about 110 million years old, which means that the Platypus-like animal was alive during the Cretaceous period, making it the oldest mammal fossil found in Australia. Monotrematum sudamericanum, another fossil relative of the Platypus, has been found in Argentina, indicating that monotremes were present in the supercontinent of Gondwana when the continents of South America and Australia were joined via Antarctica (up to about 167 million years ago).

Because of the early divergence from the therian mammals and the low numbers of extant monotreme species, it is a frequent subject of research in evolutionary biology. In 2004, researchers at the Australian National University discovered the Platypus has ten sex chromosomes, compared with two (XY) in most other mammals (for instance, a male Platypus is always XYXYXYXYXY). Although given the XY designation of mammals, the sex chromosomes of the Platypus are more similar to the ZZ/ZW sex chromosomes found in birds. The platypus genome also has both reptilian and mammalian genes associated with egg fertilisation. Lacking the mammalian sex-determining gene SRY, the process of sex determination in the Platypus remains unknown. A draft version of the platypus genome sequence was published in Nature on 8 May 2008, revealing both reptilian and mammalian elements, as well as two genes found previously only in birds, amphibians and fish. More than 80% of the Platypus' genes are common to the other mammals whose genomes have been sequenced and the study has proved that the platypus was the first species to transition from its reptilian-like ancestor to mammal.

Except for its loss from the state of South Australia, the Platypus occupies the same general distribution as it did prior to European settlement of Australia. However, local changes and fragmentation of distribution due to human modification of its habitat are documented. Its current and historical abundance, however, is less well-known and it has probably declined in numbers, although still being considered as common over most of its current range. The species was extensively hunted for its fur until the early years of the 20th century and, although protected throughout Australia in 1905, up until about 1950 it was still at risk of drowning in the nets of inland fisheries.

The Platypus does not appear to be in immediate danger of extinction thanks to conservation measures, but it could be impacted by habitat disruption caused by dams, irrigation, pollution, netting and trapping. The IUCN lists the Platypus on its Red List as Least Concern.

Platypuses generally suffer from few diseases in the wild; however, there is widespread public concern in Tasmania about the potential impacts of a disease caused by the fungus Mucor amphibiorum. The disease (termed Mucormycosis) only affects Tasmanian platypuses, and has not been observed in platypuses in mainland Australia. Affected platypuses can develop ugly skin lesions or ulcers on various parts of the body, including their backs, tails and legs. Mucormycosis can kill platypuses, death arising from secondary infection and by affecting the animals' ability to maintain body temperature and forage efficiency. The Biodiversity Conservation Branch at the Department of Primary Industries and Water are collaborating with NRM north and University of Tasmania researchers to determine the impacts of the disease on Tasmanian Platypus, as well as the mechanism of transmission and current spread of the disease. Until recently, the introduced Red Fox (Vulpes vulpes) was confined to mainland Australia, but growing evidence now indicates that it is present in low numbers in Tasmania.

Much of the world was introduced to the Platypus in 1939 when National Geographic Magazine published an article on the Platypus and the efforts to study and raise it in captivity. This is a difficult task, and only a few young have been successfully raised since—notably at Healesville Sanctuary in Victoria. The leading figure in these efforts was David Fleay, who established a platypussary—a simulated stream in a tank—at the Healesville Sanctuary and had a successful breeding in 1943. In 1972, he found a dead baby of about 50 days old, which had presumably been born in captivity, at his wildlife park at Burleigh Heads on the Gold Coast, Queensland. Healesville repeated its success in 1998 and again in 2000 with a similar stream tank. Taronga Zoo in Sydney bred twins in 2003, and had another birth in 2006.

The Platypus is sometimes jokingly referred to as proof that God has a sense of humour (at the beginning of the film Dogma, for example). Its unusual appearance has led to its featuring in many media, particularly in its native Australia.

The Platypus has been used several times as a mascot: "Syd" the Platypus was one of the three mascots chosen for the Sydney 2000 Olympics along with an echidna and a kookaburra, "Expo Oz" the Platypus was the mascot for Expo '88, which was held in Brisbane in 1988, and Hexley the Platypus is the mascot for Apple Computer's BSD-based Darwin operating system, Mac OS X.

The Platypus has also been featured in songs, such as Green Day's Platypus (I Hate You) and Mr. Bungle's Platypus. It is the subject of a children's poem by Banjo Paterson, and it also frequently appears as a character in children's television programmes, for example, the Platypus Family on Mister Rogers' Neighborhood, Perry the Platypus on the show Phineas and Ferb, and Ovide, the star of the cartoon Ovide and the Gang.

Badger

2009-06-08T20:41:00.000-07:00

Badger is the common name for a specific group of carnivorous mammals, which belong to the family Mustelidae, which also includes weasels, otters, ferrets, wolverines, and relatives. There are eight species of badger, in three subfamilies: Melinae (badgers of Europe and Asia), Mellivorinae (the Ratel or honey badger), and Taxideinae (the American badger). The Asiatic stink badgers of the genus Mydaus were formerly included in the Melinae, but recent genetic evidence indicates that these are actually relatives of the skunks (family Mephitidae).

Typical badgers (Meles, Arctonyx, Taxidea and Mellivora species) are short-legged and heavy-set. The lower jaw is articulated to the upper by means of a transverse condyle firmly locked into a long cavity of the cranium, so that dislocation of the jaw is all but impossible. This enables the badger to maintain its hold with the utmost tenacity, but limits its jaw movement to hingeing opening and shutting or sliding from side to side.

The behavior of badgers differs by family, but all shelter underground, living in burrows called setts. Some are solitary, moving from home to home, while others are known to form clans. Clan size is variable from 2 to 15.

Badgers are fierce animals and will protect themselves and their young at all costs. Badgers are capable of fighting off much larger animals such as wolves, coyotes and bears. Badgers can run or gallop at up to 25–30 km per hour for short periods of time.

North American Badgers (Taxidea taxus) and Coyotes (Canis latrans) have been seen hunting together, in a cooperative fashion.

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American Badgers are fossorial carnivores. Unlike many carnivores that stalk their prey in open country, badgers catch most of their food by digging. They can tunnel after ground dwelling rodents with amazing speed. They have been known to cache food.

The diet of the Eurasian badger consists largely of earthworms, insects, and grubs. They also eat small mammals, amphibians, reptiles and birds as well as cereals, roots and fruit.

The honey badger consumes honey, porcupines and even venomous snakes (such as the puff adder). They will climb trees to gain access to honey from bees' nests.

In North America, coyotes sometimes eat badgers and vice versa, but the majority of their interactions seem to be mutual or neutral.

Hunting badgers is common in many countries. Manipulating the badger population is prohibited in many European countries as badgers are listed in the Berne Convention, but they are not otherwise the subject of any international treaty or legislation.

The blood sport of badger-baiting was outlawed in the United Kingdom by the Cruelty to Animals Act 1835 as well as the Protection of Badgers Act 1992 which makes it a serious offence to kill, injure or take a badger, or to damage or interfere with a sett unless a licence is obtained from a statutory authority. An exemption that allowed fox hunters to loosely block setts to prevent chased foxes escaping into them was brought to an end with the passage of the Hunting Act 2004.

Many badgers in Europe were gassed during the 1960s and 1970s to control rabies. Until the 1980s, gassing was also practised in the UK to control the spread of bovine TB.

Scandinavian custom is to put eggshells or styrofoam in one's boots when walking through badger territory, as badgers are believed to bite down until they can hear a crunch. The dachshund dog breed has a history with badgers; "dachs" is the German word for badger, and dachshunds were originally bred to be badger hounds.

The badger is the state animal of Wisconsin. Likenesses of badgers appear through the Wisconsin State Capitol, and a badger appears on the head of the statue of Wisconsin atop the building. The official mascot of the University of Wisconsin-Madison is Buckingham U. Badger, AKA Bucky Badger.

Today badgers are commercially raised for their hair, which is harvested to make shaving brushes. Because badgers are a protected species in North America and most of Europe, virtually all commercial badger hair comes from mainland China, which supplies knots of hair in three grades to brush makers in both China and Europe. In rural Northern China, badgers multiply to the point of becoming a crop nuisance, and village cooperatives are licensed by the national government to hunt badgers and process their hair. The hair is also used for paint brushes, and was used as a trim on Native American garments. It has been used in some instances as doll hair.

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Boar

2009-06-08T17:01:00.000-07:00

The wild boar (Sus scrofa) or wild hog, often simply referred to as a boar, is a species of a pig in the biological family Suidae and the wild ancestor of the domestic pig. It is native across much of Central Europe, the Mediterranean Region (including North Africa's Atlas Mountains) and much of Asia as far south as Indonesia, and has been introduced elsewhere.

Although common in France, the wild boar became extinct in Great Britain and Ireland by the 17th century, but wild breeding populations have recently returned in some areas, particularly the Weald, following escapes from boar farms.

The term boar is used to denote an adult male of certain species—including, confusingly, domestic pigs. However, for wild boar, it applies to the whole species, including, for instance, "sow wild boar" or "wild boar piglet".

The body of the wild boar is compact; the head is large, the legs relatively short. The fur consists of stiff bristles and usually finer fur. The colour usually varies from dark grey to black or brown, but there are great regional differences in colour; even whitish animals are known from central Asia. During winter the fur is much denser.

Adult boars average 120–180 cm in length and have a shoulder height of 90 cm. As a whole, their average weight is 50–90 kg kilograms (110–200 pounds), though boars show a great deal of weight variation within their geographical ranges. In central Italy their weight usually ranges from 80 to 100 kg; boars shot in Tuscany have been recorded to weigh 150 kg (331 lb). A French specimen shot in Negremont forest in Ardenne in 1999 weighed 227 kg (550 lb).

Carpathian boars have been recorded to reach weights of 200 kg (441 lb), while Romanian and Russian boars can reach weights of 300 kg (661 lb). Generally speaking, native Eurasian boars follow the Bergmann's rule, with smaller boars nearer the tropics and larger, smaller-eared boars in the North of their range.

The continuously growing tusks (the canine teeth) serve as weapons and tools. The lower tusks of an adult male measure about 20 cm (7.9 in) (from which seldom more than 10 cm (3.9 in) protrude out of the mouth), in exceptional cases even 30 cm (12 in). The upper tusks are bent upwards in males, and are regularly ground against the lower ones to produce sharp edges. In females they are smaller, and the upper tusks are only slightly bent upwards in older individuals.

Wild boar piglets are coloured differently from adults, being a soft brown with longitudinal darker stripes. The stripes fade by the time the piglet is about half-grown, when the animal takes on the adult's grizzled grey or brown colour.

Litter size of wild boars may vary depending on their location. A study in the Great Smokey Mountains National Park in the US reported a mean litter size of 3.3. A similar study on Santa Catalina Island, California reported a mean litter size of 5. Larger litter sizes have been reported in Europe.

Wild boars live in groups called sounders. Sounders typically[weasel words] contain around 20 animals, but groups of over 50 have been seen. In a typical sounder there are two or three sows and their offspring; adult males are not part of the sounder outside of a breeding cycle, two to three per year, and are usually found alone. Birth, called farrowing, usually occurs in a secluded area away from the sounder; a litter will typically contain 8–12 piglets.

The animals are usually nocturnal, foraging from dusk until dawn but with resting periods during both night and day. They eat almost anything they come across, including grass, nuts, berries, carrion, roots, tubers, refuse, insects, small reptiles—even young deer and lambs.

Boars are the only hoofed animals known to dig burrows.

If surprised or cornered, a boar (and particularly a sow with her piglets) can and will defend itself and its young with intense vigor. The male lowers its head, charges, and then slashes upward with his tusks. The female, whose tusks are not visible, charges with her head up, mouth wide, and bites. Such attacks are not often fatal to humans, but may result in severe trauma, dismemberment, or blood loss.

The wild boar was originally found in North Africa and much of Eurasia from the British Isles to Korea and the Sunda Islands. In the north it reached southern Scandinavia and southern Siberia. Within this range it was absent in extremely dry deserts and alpine zones.

A few centuries ago it was found in North Africa along the Nile valley up to Khartum and north of the Sahara. The reconstructed northern boundary of the range in Asia ran from Lake Ladoga (at 60°N) through the area of Novgorod and Moscow into the southern Ural, where it reached 52°N. From there the boundary passed Ishim and farther east the Irtysh at 56°N. In the eastern Baraba steppe (near Novosibirsk) the boundary turned steep south, encircled the Altai Mountains, and went again eastward including the Tannu-Ola Mountains and Lake Baikal. From here the boundary went slightly north of the Amur River eastward to its lower reaches at the China Sea. At Sachalin there are only fossil reports of wild boar. The southern boundaries in Europe and Asia were almost everywhere identical to the sea shores of these continents. In dry deserts and high mountain ranges, the wild boar is naturally absent. So it is absent in the dry regions of Mongolia from 44–46°N southward, in China westward of Sichuan and in India north of the Himalaya. In high altitudes of Pamir and Tien Shan they are also absent; however, at Tarim basin and on the lower slopes of the Tien Shan they do occur.

Domestic pigs quite readily become feral, and feral populations often revert to a similar appearance to wild boar; they can then be difficult to distinguish from natural or introduced true wild boar (with which they also readily interbreed). The characterization of populations as feral pig, escaped domestic pig or wild boar is usually decided by where the animals are encountered and what is known of their history. In New Zealand, for example, feral pigs are known as "Captain Cookers" from their supposed descent from liberations and gifts to Māori by explorer Captain James Cook in the 1770s. New Zealand feral pigs are also frequently known as "tuskers", due to their appearance.

One characteristic by which domestic and feral animals are differentiated is their coats. Feral animals almost always have thick, bristly coats ranging in colour from brown through grey to black. A prominent ridge of hair matching the spine is also common, giving rise to the name razorback in the southern United States, where they are common. The tail is usually long and straight. Feral animals tend also to have longer legs than domestic breeds and a longer and narrower head and snout.

A very large swine dubbed Hogzilla was shot in Georgia, USA in June 2004. Initially thought to be a hoax, the story became something of an internet sensation. National Geographic Explorer investigated the story, sending scientists into the field. After exhuming the animal and performing DNA testing, it was determined that Hogzilla was a hybrid of wild boar and domestic swine.

At the beginning of the 20th century, wild boar were introduced for hunting in the United States, where they interbred in parts with free roaming domestic pigs. In South America, New Guinea, New Zealand, Australia and other islands, wild boar have also been introduced by humans and have partially interbred with domestic pigs.

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In South America, also during the early 20th century, free-ranging boars were introduced in Uruguay for hunting purposes and eventually crossed the border into Brazil sometime during the 1990s, quickly becoming an invasive species, licensed private hunting of both feral boars and hybrids (javaporcos) being allowed from August 2005 on in the Southern Brazilian state of Rio Grande do Sul, although their presence as a pest had been already noticed by the press as early as 1994. Releases and escapes from unlicensed farms (established because of increased demand for boar meat as an alternative to pork), however, continued to bolster feral populations and by mid-2008 licensed hunts had to be expanded to the states of Santa Catarina and São Paulo.

Recently-established Brazilian boar populations are not to be confused with long established populations of feral domestic pigs (porcos monteiros), which have existed mainly in the Pantanal for more than a hundred years, along with native peccaries. The demographic dynamics of the interaction between feral pigs populations and those of the two native species of peccaries (Collared Peccary and White-lipped Peccary) is obscure and is being studied presently.

It has been proposed that the existence of feral pigs could somewhat ease jaguar predation on peccary populations, as jaguars would show a preference for hunting pigs, when these are available.

As of 2008, the estimated population of 4 million feral hogs cause an estimated US$800 million of property damage a year in the U.S.

Wild boar are a main food source for tigers in the regions where they coexist. Tigers typically follow boar herds, and pick them off one by one. In some cases, whole herds have been destroyed in this manner. Tigers have been noted to chase boars for longer distances than with other prey, though they will usually avoid tackling mature male boars. In some rare cases, boars have gored tigers to death in self defense.

Wolves are also major predators of boars in some areas. Wolves mostly feed on piglets, though adults have been recorded to be taken in Italy, the Iberian Peninsula and Russia. Wolves rarely attack boars head on, preferring to tear at their perineum, causing loss of coordination and massive blood loss. In some areas of the former Soviet Union, a single wolf pack can consume an average of 50–80 wild boars annually. In areas of Italy where the two animals are sympatric, the extent to which boars are preyed upon by wolves has led to them developing more aggressive behaviour toward both wolves and domestic dogs.

Striped hyenas occasionally feed on boars, though it has been suggested that only hyenas from the three larger subspecies present in Northwest Africa, the Middle East and India can successfully kill them.

Young piglets are important prey for several species, including large snakes, such as the reticulated python, large birds of prey and various wild felids. Adults, due to their size, strength and defensive aggression, are generally avoided as prey except by wolves and tigers. However, they have been taken additionally by leopards; large bears (mainly brown bears); and mature crocodiles. All predators of boars are opportunistic and would take piglets given the opportunity. Where introduced outside of their natural range, boars may be at the top of the food chain, but are also sometimes taken by predators similar to those in their native Eurasia.

In Greek mythology, two boars are particularly well known. The Erymanthian Boar was hunted by Heracles as one of his Twelve Labours, and the Calydonian Boar was hunted in the Calydonian Hunt by dozens of other mythological heroes, including some of the Argonauts and the huntress Atalanta. Ares, the Greek god of war, had the ability to transform himself into a wild boar, and even gored his son to death in this form to prevent the young man from growing too attractive and stealing his wife.

In Celtic mythology the boar was sacred to the Gallic goddess Arduinna, and boar hunting features in several stories of Celtic and Irish mythology. One such story is that of how Fionn mac Cumhaill ("Finn McCool") lured his rival Diarmuid Ua Duibhne to his death—gored by a wild boar.

In the Asterix comic series set in Gaul, wild boar are the favourite food of Obelix whose immense appetite means that he can eat several roasted boar in a single sitting.

The Norse gods Freyr and Freyja both had boars. Freyr's boar was named Gullinbursti ("Golden Mane"), who was manufactured by the dwarf Sindri due to a bet between Sindri's brother Brokkr and Loki. The bristles in Gullinbursti's mane glowed in the dark to illuminate the way for his owner. Freya rode the boar Hildesvini (Battle Swine) when she was not using her cat-drawn chariot. According to the poem Hyndluljóð, Freyja concealed the identity of her protégé Óttar by turning him into a boar. In Norse mythology, the boar was generally associated with fertility.

In Persia (Iran) during the Sassanid Empire, boars were respected as fierce and brave creatures, and the adjective "Boraz (Goraz)" (meaning boar) was sometimes added to a person's name to show his bravery and courage. The famous Sassanid spahbod, Shahrbaraz, who conquered Egypt and the Levant, had his name derived Shahr(city) + Baraz(boar like/brave) meaning "Boar of the City".

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In Hindu mythology, the third avatar of the Lord Vishnu was Varaha, a boar.

In Chinese horoscope the boar (sometimes also translated as pig), is one of the twelve animals of the zodiac, based on the legends about its creation, either involving Buddha or the Jade Emperor.

In Islamic faith when the wrath of God was unleashed upon the nation of Dawood(David), they were turned into boars and monkeys. God has ordered the Israelite to worship on Saturday; Israelites who were into fishing at that time would lay their nets on Friday night, and come back on Sunday to collect the fish. God ordered Dawood to exile them outside the city and build a wall around them. A week later when he went to set them free, they were all turned into swines and monkeys.

At least three Roman Legions are known to have had a boar as their emblems: Legio I Italica, Legio X Fretensis and Legio XX Valeria Victrix. X Fretensis was centrally involved in the First Jewish–Roman War, culminating with the destruction of Jerusalem and the Jewish Temple in 70 AD. In addition, it was stationed in Roman-occupied Judea for centuries and was involved in numerous other acts of oppression against the Jews. By one theory, resentment of this Legion's boar emblem, which came to be identified with extreme destruction and persecution, partly accounts for the deep-rooted traditional Jewish aversion for pork. (The Bible does not single out pigs in comparison with the many other unclean animals whose flesh is forbidden; nevertheless, in actual Jewish culture pigs are clearly singled out for a special, highly emotional loathing, of a kind not directed at other unclean animals).

A boar is a long-standing symbol of the city of Milan, Italy. In Andrea Alciato's Emblemata (1584), beneath a woodcut of the first raising of Milan's city walls, a boar is seen lifted from the excavation. The foundation of Milan is credited to two Celtic peoples, the Bituriges and the Aedui, having as their emblems a ram and a boar respectively; therefore "The city's symbol is a wool-bearing boar, an animal of double form, here with sharp bristles, there with sleek wool." Alciato credits the most saintly and learned Ambrose for his account.

The ancient Lowland Scottish Clan Swinton is said to have to have acquired the name Swinton for their bravery and clearing their area of Wild Boar. The chief's coat of arms and the clan crest allude to this legend, as is the name of the village of Swinewood in the county of Berwick which was granted to them in the Eleventh Century.

Richard III (r. 1483–1485) used the white boar as his personal heraldic device and symbol. It was also passed to his short-lived son, Edward.

The wild boar and a boar's head are common charges in heraldry. It represents what are often seen as the positive qualities of the boar, namely courage and fierceness in battle.

Bobcat

2009-06-07T19:17:00.000-07:00

The Bobcat (Lynx rufus) is a North American mammal of the cat family, Felidae. With twelve recognized subspecies, it ranges from southern Canada to northern Mexico, including most of the continental United States. The Bobcat is an adaptable predator that inhabits wooded areas, as well as semi-desert, urban edge, forest edges and swampland environments. It persists in much of its original range and populations are healthy.

With a gray to brown coat, whiskered face, and black-tufted ears, the Bobcat resembles the other species of the mid-sized Lynx genus. It is smaller than the Canadian Lynx, with which it shares parts of its range, but is about twice as large as the domestic cat. It has distinctive black bars on its forelegs and a black-tipped, stubby tail, from which it derives its name.

Though the Bobcat prefers rabbits and hares, it will hunt anything from insects and small rodents to deer. Prey selection depends on location and habitat, season, and abundance. Like most cats, the bobcat is territorial and largely solitary, although there is some overlap in home ranges. It uses several methods to mark its territorial boundaries, including claw marks and deposits of urine or feces. The Bobcat breeds from winter into spring and has a gestation period of about two months.

Although the Bobcat have been subject to extensive hunting by humans, both for sport and fur, its population has proven resilient. The elusive predator features in Native American mythology and the folklore of European settlers.

There had been debate over whether to classify this species as Lynx rufus or Felis rufus as part of a wider issue regarding whether the four species of Lynx should be given their own genus, or be placed as a subgenus of Felis. The Lynx genus is now accepted, and the Bobcat is listed as Lynx rufus in modern taxonomic sources.

Johnson et al. report that Lynx shared a clade with the Puma, Leopard Cat (Prionailurus), and Domestic Cat (Felis) lineages, dated to 7.15 million years ago (mya); Lynx diverged first, approximately 3.24 mya.

The Bobcat is believed to have evolved from the Eurasian Lynx, which crossed into North America by way of the Bering land bridge during the Pleistocene, with progenitors arriving as early as 2.6 mya. The first wave moved into the southern portion of North America, which was soon cut off from the north by glaciers. This population evolved into modern Bobcats around 20,000 years ago. A second population arrived from Asia and settled in the north, developing into the modern Canadian Lynx. Hybridization between the Bobcat and the Canadian lynx may sometimes occur.

The Bobcat resembles other species of the Lynx genus but is on average the smallest of the four. Its coat is variable, though generally tan to grayish brown, with black streaks on the body and dark bars on the forelegs and tail. Its spotted patterning acts as camouflage. The ears are black-tipped and pointed, with short black tufts. There is generally an off-white color on the lips, chin, and underparts. Bobcats in the desert regions of the southwest have the lightest colored coats, while those in the northern, forested regions are darkest. Kittens are born well-furred and already have their spots. A few melanistic Bobcats have been sighted and captured in Florida. They appear black, but may actually still exhibit a spot pattern.

The face appears wide due to ruffs of extended hair beneath the ears. The fur is brittle but quite long and dense. The nose of the Bobcat is pinkish-red, and it has a base color of gray or yellowish- or brownish-red on its face, sides, and back. Bobcat eyes are yellow with black pupils. The pupils are elongated vertically and will widen during nocturnal activity to maximize light reception. The cat has sharp hearing and vision, and a good sense of smell. It is an excellent climber, and will swim when it needs to, but will normally avoid water.

The adult male Bobcat is 28 to 47 inches (70–120 cm) long, averaging 36 inches (90 cm); this includes a stubby 4 to 7 inch (10–18 cm) tail, which has a "bobbed" appearance and gives the species its name. An adult stands about 20 to 24 inches (51–61 cm) at the shoulders. Adult males usually range from 16 to 30 pounds (7–14 kg); females average about 20 pounds (9 kg). The largest bobcat on recorded weighed 48.9 pounds (22.2 kg). The Bobcat is muscular, and its hind legs are longer than its front legs, giving it a bobbing gait. At birth it weighs 0.6 to 0.75 pounds (280–340 g) and is about 10 inches (25 cm) in length. By its first year it will reach about 10 pounds (4.5 kg).

The cat is larger in its northern range and in open habitats. A morphological size comparison study in the eastern United States found a divergence in the location of the largest male and female specimens, suggesting differing selection constraints for the sexes.

The Bobcat is crepuscular (generally most active at twilight and dawn). It keeps on the move from three hours before sunset until about midnight, and then again from before dawn until three hours after sunrise. Each night it will move from 2 to 7 miles (3–11 km) along its habitual route. This behavior may vary seasonally, as Bobcats become more diurnal during fall and winter. This is a response to the activity of their prey, which are more active during the day in colder months.

Bobcat activities are confined to well-defined territories, which vary in size depending on gender and the distribution of prey. The home range is marked with feces, urine scent, and by clawing prominent trees in the area. In its territory the Bobcat will have numerous places of shelter: usually a main den, and several auxiliary shelters on the outer extent of its range, such as hollow logs, brush piles, thickets, or under rock ledges. Its den smells strongly of the Bobcat.

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The sizes of Bobcat's home ranges vary significantly; a World Conservation Union (IUCN) summary of research suggests ranges anywhere from 0.02 to 126 sq mi (0.6 to 326 km²). One study in Kansas found resident males to have roughly an 8 sq mi (20 km²) range and females less than half that area. Transient Bobcats were found to have both a larger (roughly 22 sq mi/57 km2) and less well-defined home range. Kittens had the smallest range at about 3 sq mi (7 km²). Research has shown that dispersal from the natal range is most pronounced with males.

Reports on seasonal variation in range size have been equivocal. One study found a large variation in male range sizes, from 16 sq mi (41 km²) in summer up to 40 sq mi (100 km²) in winter. Another found that female Bobcats, especially those which were reproductively active, expanded their home range in winter, but that males merely shifted their range without expanding it, which was consistent with numerous earlier studies. Other research in various American states has shown little or no seasonal variation.

Like most felines, the Bobcat is largely solitary but ranges will often overlap. Unusually for a cat, males are more tolerant of overlap, while females rarely wander into others' ranges. Given their smaller range sizes, two or more females may reside within a male's home range.

When multiple male territories overlap a dominance hierarchy is often established resulting in the exclusion of some transients from favored areas.

In line with widely differing estimates of home range size, population density figures are divergent: anywhere from 1 to 38 Bobcats per 25 sq mi (65 km²) in one survey. The average is estimated at one Bobcat per every 5 sq mi (13 km²), or slightly less. A link has been observed between population density and sex ratio. One study noted that a dense, unharvested population in California had a sex ratio of 2.1 males per female. When the density decreased, the sex ratio skewed to 0.86 males per female. Another study observed a similar ratio, and suggested that males may be better able to cope with the increased competition, and that this would help limit reproduction until various factors lowered the density.

The Bobcat is able to go for long periods without food, but will eat heavily when prey is abundant. During lean periods, it will often prey on larger animals that it can kill and return to feed on later. The Bobcat hunts by stalking its prey and then ambushing it with a short chase or pounce. Its preference is for mammals about 1.5 to 12.5 pounds (0.7 to 5.7 kg). Its main prey varies by region. In the eastern United States it is the Eastern Cottontail species, and in the north it is the Snowshoe Hare. When these prey species exist together, as in New England, they are the primary food sources of the Bobcat. In the far south, the rabbits and hare are sometimes replaced by Cotton Rats as the primary food source. The Bobcat is an opportunistic predator that, unlike the more specialized Canadian Lynx, will readily vary its prey selection. Research has shown that diet diversification positively correlates to a decline in numbers of the Bobcat's principal prey; the abundance of its main prey species is the main determinant of overall diet.

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The Bobcat hunts animals of different sizes, and will adjust its hunting techniques accordingly. With small animals, such as rodents, squirrels, birds, fish and insects, it will hunt in areas known to be abundant in prey, and will lie, crouch, or stand and wait for victims to wander close. It will then pounce, grabbing its prey with its sharp, retractable claws. For slightly larger animals, such as rabbits and hares, it will stalk from cover and wait until they come within 20 to 35 feet (6 to 10 m) before rushing in to attack. Less commonly it will feed on larger animals such as foxes, minks, skunks, small dogs and domesticated cats. Bobcats are considered the major predatory threat to the endangered Whooping Crane. Bobcats are also occasional hunters of livestock and poultry. While larger species such as cattle and horses are not known to be attacked, Bobcats do present a threat to smaller ruminants such as sheep and goats. According to the National Agricultural Statistics Service, Bobcats killed 11,100 sheep in 2004, comprising 4.9% of all sheep predator deaths. However, some amount of Bobcat predation may be misidentified, as Bobcats have been known to scavenge on the remains of livestock kills by other animals.

It has been known to kill deer, especially in winter when smaller prey is scarce, or when deer populations become more abundant. One study in the Everglades showed a large majority of kills (33 of 39) were fawns, but that prey up to eight times the Bobcat's weight could be successfully taken. It stalks the deer, often when the deer is lying down, then rushes in and grabs it by the neck before biting through the throat, base of the skull, or chest. On the rare occasions that a Bobcat kills a deer, it eats its fill and then buries the carcass under snow or leaves, often returning to it several times to feed.

The Bobcat prey base overlaps with that of other mid-sized predators of a similar ecological niche. Research in Maine has shown little evidence of competitive relationships between the Bobcat and Coyote or Red Fox; separation distances and territory overlap appeared random amongst simultaneously monitored animals. With the Canadian Lynx, however, the interspecific relationship affects distribution patterns: competitive exclusion by the Bobcat is likely to have prevented any further southward expansion of the range of its felid cousin.

Bobcats typically live to six or eight years of age, with a few reaching beyond ten. The longest they have been known to live is 16 years in the wild and 32 years in captivity.

Wild Cats

2009-06-07T15:18:00.000-07:00

The Wildcat (Felis silvestris), sometimes Wild Cat or Wild-cat, is a small felid native to Europe, the western part of Asia, and Africa. It is a hunter of small mammals, birds, and other creatures of a similar size. There are several subspecies distributed in different regions. Sometimes included is the ubiquitous domestic cat (Felis silvestris catus), which has been introduced to every habitable continent and most of the world's larger islands, and has become feral in many of those environments.

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In its native environment, the Wildcat is adaptable to a variety of habitat types: savanna, open forest, and steppe. Although domesticated breeds show a great variety of shapes and colours, wild individuals are medium-brown with black
stripes, between 45 and 80 cm (18–32 inches) in length, and weigh between 3 and 8 kilograms (6–17.6 pounds). Shoulder height averages about 35 cm (14 in) and tail length is about 30 cm (12 in). The African subspecies tends to be a little smaller and a lighter brown in colour.

The Wildcat is extremely timid. It avoids approaching human settlements. It lives solitarily and holds a territory of about 3 km².

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A study by the National Cancer Institute suggests that all current house cats in the world are descendants from a group of self-domesticating Wildcats 10,000 years ago, somewhere in the Near East. The closest relative of the Wildcat is the Sand Cat (Felis margarita).

It is an obligate carnivore, like all felines, and consumes almost every part of any kill it makes; the bones calcium, and the meat everything else; in fact, they rarely need to drink because meat has such a high water content.When we look at the domestic cat today we can still see many of the features of their wild ancestry. Indeed, cats today, from the domestic cat to the big cats, are descendants of the Carnivorous known as the Miacids. (Some of the Miacids became cheetahs, lions and tigers.)

The Martelli's wild cat is believed to be the ancestor of the modern small cat, which resulted in the modern wild cat. The wild cat can be categorized into sub sections; the European Wild Cat, the Asiatic desert Cat and the African Wild Cat. Our much loved domestic cat is thought to be a descendant of the African Wild Cat.

Tamarin

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The tamarins are any of the squirrel-sized New World monkeys from the family Callitrichidae, classified as the genus Saguinus. The closely related lion tamarins are in genus Leontopithecus.

Tamarin habitats range from southern Central America (Costa Rica) through middle South America (Amazon basin and north Bolivia, however not in the mountainous parts).

The various species of tamarins differ considerably according to their appearance, ranging from nearly all black through mixtures of black, brown and white. Many species typically have mustache-like facial hairs. Their body size ranges from 18 to 30 cm (plus a 25 to 44 cm long tail) and they weigh from 220 to 900 grams. Tamarins differ from marmosets primarily in the fact that the lower canine teeth are clearly longer than the incisors.

Tamarins are inhabitants of tropical rain forests and open forest areas. They are diurnal and arboreal, and run and jump quickly through the trees. Tamarins live together in groups of up to 40 members consisting of one or more families. More frequently, though, groups are composed of just three to nine members.

Tamarins are omnivores, eating fruits and other plant parts as well as spiders, insects, small vertebrates and bird eggs.

Gestation is typically 140 days, and births are normally twins. The father primarily cares for the young, bringing them to their mother to nurse. After approximately one month the young begin to eat solid food, although they aren't fully weaned for another two to three months. They reach full maturity in their second year. In captivity, tamarins live to be 18 years old.

Slightly smaller than squirrels, tamarins are commonly called "kings of the jungle" because manes around their faces make them look like lions. All of the species (members) of this family have claws that they use to dig under bark to gather meals of insects.

Tamarins live in family groups. Parents mate once a year producing two offspring (babies) per birth. The older twins stay a long time with their family helping their parents take care of the children. Both parents care for new-borns. The father takes care of the tiny babies by carrying them on his back. Mothers nurse babies every two to three hours.

Tamarins are omnivores, meaning they like to eat both plants and animals. They spend a lot of their day looking for their favorite foods like small fruits, insects like wild roaches, and even small lizards and snakes.

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Found only in the Atlantic Rainforests of Brazil, these tiny monkeys are critically endagered. Captive breeding, managed wild breeding, translocations, and re-introduction are some of the strategies being used to save lion tamarins.

Lion tamarins have a mane derived from long hairs on the top of the head, cheeks and throat. The golden lion tamarin's color is predominantly golden with occasional orange, brown or black coloration on the tail and forepaws.

It weighs about 0.5 kg (1.1 lb) and averages about 25 cm (10") in head/body length, not counting the tail.

The golden lion tamarin prefers primary lowland tropical forest from sea level to 1000 m (3300'). Golden lion tamarins are omnivorous, feeding on fruits, gum, nectar, insects, and small vertebrates. The golden lion tamarin is diurnal and predominantly arboreal. It is usually found at heights of 3 - 10 m (10 - 30') above the forest floor.

It sleeps there at night in tangled vegetation or, more often, in a hole in a tree, such as an abandoned woodpecker nest.

Most golden lion tamarins live in reproductive groups that occupy stable territories. The average number of individuals/group in one study was 5.4. In the wild, groups usually consist of one breeding adult of each sex and younger animals. Golden lion tamarins are cooperative breeders: all adult members of a group help to carry and feed the offspring of the group, with the adult male commonly doing the largest share. The mother only takes the babies to nurse them.

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In the 19th century, the golden lion tamarin occurred in Brazil in the coastal forests of the states of Rio de Janeiro and Espirito Santo. By the early 1980's it was known only from remnant forests in the state of Rio de Janeiro in an area of occupied habitat probably totaling considerably less than 900 sq km (350 sq mi). The wild population is currently fragmented into 17 different subpopulations in isolated forest patches throughout its small range.

More than 90% of the original Atlantic coastal forest, which contains the golden lion tamarin's habitat, has been lost or fragmented to obtain lumber and charcoal and to clear out areas for plantations, cattle pasture, and development. Capture for zoos and private collections also contributed to its decline in the past. The golden lion tamarin is still under severe threat from continued deforestation, much of which is undertaken to create weekend beach properties. Less than 2% of the forest remains in the region where the golden lion tamarin lives.

A tamarin group actively delineates the boundaries of its territory to warn other tamarins against entering it. This is accomplished through vocalizations and scent marking during ritualized group encounters. Actual fighting does not occur.

Porcupine

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Porcupines are rodents with a coat of sharp spines, or quills, that defend them from predators. They are endemic in both the Old World and the New World. Porcupines are the third largest of the rodents, behind the capybara and the beaver. Most porcupines are about 25–36 in (630–910 mm) long, with an 8–10 in (200–250 mm) long tail. Weighing between 12–35 lb (5.4–16 kg), they are rounded, large and slow. Porcupines come in various shades of brown, grey, and the unusual white. Porcupines' spiny protection resembles that of the unrelated erinaceomorph hedgehogs and monotreme echidnas.

A porcupine is any of 27 species of rodent belonging to the families Erethizontidae or Hystricidae. Porcupines vary in size considerably: Rothschild's Porcupine of South America weighs less than a kilogram (2.2 lb (1.00 kg)); the African Porcupine can grow to well over 10 kg (22 lb). The two families of porcupines are quite different and although both belong to the Hystricognathi branch of the vast order Rodentia, they are not closely related.

The eleven Old World porcupines are almost exclusively terrestrial, tend to be fairly large, and have quills that are grouped in clusters. They are believed to have separated from the other hystricognaths about 30 million years ago, much earlier than the New World porcupines.

The twelve New World porcupines are mostly smaller (although the North American Porcupine reaches about 85 cm/33 in in length and 18 kg/40 lb), have their quills attached singly rather than grouped in clusters, and are excellent climbers, spending much of their time in trees. The New World porcupines evolved their spines independently (through convergent evolution) and are more closely related to several other families of rodent than they are to the Old World porcupines. Porcupines have a relatively high longevity and until recently held the record for being the longest living rodent, recently broken by the Naked Mole Rat.

Porcupines' quills or spines take on various forms, depending on the species, but all are modified hairs coated with thick plates of keratin, and they are embedded in the skin musculature. Old World porcupines (Hystricidae) have quills embedded in clusters, whereas in New World porcupines (Erethizontidae) single quills are interspersed with bristles, underfur, and hair.

Porcupine quills are as sharp as needles, detach very easily, and will remain embedded in an attacker. Unlike needles, however, the quills of porcupines have microscopic, backwards-facing barbs on the tip that catch on the skin making them difficult and painful to extract. Quills are about 75 millimeters (3.0 in) long and 2 millimeters (0.079 in) in width. If a quill becomes lodged in the tissues of an animal, the barbs act to pull the quill further into the tissues with the normal muscle movements of that animal, moving up to several millimeters in a day.

Predators have been known to die as a result of quill penetration and infection. Quills are still capable of penetrating animals after death.

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Quills are released by contact with them, or they may drop out when the porcupine shakes its body, but cannot be projected at attackers, contrary to popular belief. New quills grow to replace lost ones.

Porcupines occupy a wide range of habitats in tropical and temperate parts of Asia, Italy, Africa, and North and South America. Porcupines live in forests, deserts, rocky outcrops, hillsides and grasslands. Some new world porcupines live in trees, but old world porcupines stay on the ground. Porcupines can be found on rocky areas up to 3,500 m (11,000 ft) high. Porcupines are nocturnal.

Porcupines in search of salt sometimes encroach on human habitats, eating plywood cured with sodium nitrate, certain paints, and tool handles, footwear, clothes and other items that have been coated in salty sweat. Porcupines are attracted to roads in areas where rock salt is used to melt ice and snow, and are known to gnaw on vehicle tires or wiring coated in road salt. Salt licks placed nearby can prevent porcupines from injuring themselves.

Natural sources of salt consumed by porcupines include varieties of salt-rich plants (such as yellow water lily and aquatic liverwort), fresh animal bones, outer tree bark, mud in salt-rich soils, and objects imbued with urine.

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The name "porcupine" comes from Middle French porc d'épine which could be translated as "thorny", "spined", or "quilled" "pork" or "pig", hence the nickname "quill pig" for the animal.

A group of porcupines is called a "prickle". From ancient times it was believed that porcupines can throw their quills at an enemy. This has long been refuted, being the result of loose quills being shaken free.

The North American, or Canadian, tree porcupine, Erethizon dorsatum, is found in wooded areas over most of North America, excluding the SE United States. This animal has a coat of long, shaggy, brown or black hair mixed with shorter quills. When threatened it erects its quills and backs toward its enemy, delivering a blow with its tail.

Even if no contact is made quills may fly out; this has given rise to the erroneous belief that porcupines can shoot their quills. North American porcupines spend the day, singly or in groups, in rock cavities, hollow logs, or burrows. At night they forage in trees, feeding on leaves, buds and bark. They subsist in winter entirely on bark stripped from evergreens. The damage they do to trees is conspicuous, but seldom fatal.