Class: MAMMALIA

Order: CARNIVORA

Family: URSIDAE

Genus: URSUS

Species: MARITIMUS

The largest of the eight species of bear; as well as the largest predatorial land-animal - a male polar bear may grow up to 1.5 metres at the shoulder, a size apparently doubled when the bear stands upon its hind-legs, and 3 metres in length, weighing up to 770 kilograms. Polar bears are rivaled in size only by the Kodiak bears of Alaska - which may grow to a similar [or larger] size, though weigh considerably less. The modern species of polar bear is not thought to have existed for more than 500,000 years, and it is believed that the species diverged from the brown bear of Europe - meaning that several key factors to the species' survival as the northernmost species of bear have occurred considerably rapidly in timescale; found in areas surrounding the Arctic Circle. A fossil has been uncovered in Norway's Svalbard archipelago of a jawbone dating 120,000 years - indicating that by this time, the jawbone had developed to a substantial level to support a hypercarnivorous living. Its genus, Ursus, is shared with brown and American black bears.

Polar bears incorporate a similar body-plan to other species of bear - as direct descendants of brown bears, the anatomy of the polar bear is much like that of the brown species, with a thick snout, smallish, rounded head, and muscular body. Native to greatly different habitat, however, the morphology of polar bears also differs in various manners than their brown relatives. One notable difference is that the fur of the polar bear appears white as so to camouflage the animal, assisting in hunting prey. The fur contains no white pigment - the hairs are hollow and transparent, and merely reflect the light given off by the sun, which is mostly white-coloured. As do a number of mammals, Polar bears possess two layers of fur - coarse, hollow guard hairs and less hollow undercoat hairs, which also lack pigment. Below the layers of fur lies black skin, which absorbs the heat given by the sun, allowing for an efficient source of heat. The black skin is especially evident on the nose of a polar bear, one part not covered completely by fur. Heat absorbtion in such a manner can even lead to overheating in polar bears - which use swimming in colder Arctic waters [typically at freezing temperature] as a means of cooling off.