Origin of the species
Initially it was assumed that the polar bear separated from brown about 45-150 thousand years ago, probably in the territory of modern Ireland. However , a recent study showed that the polar bear separated from their common ancestor with brown bear 338-934 thousand years ago ( an average of 600 thousand years ago) , and 100-120 thousand years ago by crossing species representatives took their hybridization , resulting in all modern polar bears are descended from these hybrids .Appearance
Head bears. From left to right : Brown , Black, White .Polar bear - one of the largest terrestrial carnivorous mammals of Representatives . Its length is 3 m , weight up to 1 ton Usually males weigh 400-450 kg , body length of 200-250 cm, height at the withers 130-150 cm Females noticeably smaller ( 200-300 kg). The smallest bears are found on Spitsbergen , the largest - in the Bering Sea .Polar bear from other bears distinguish long neck and flat head . His skin is black. Fur color varies from white to yellowish ; summer fur may turn yellow due to constant exposure to sunlight . Polar bear fur is devoid of pigment stains, and hollow hairs . Translucent hairs allows only ultraviolet rays, giving the coat insulating properties . When ultraviolet photography polar bear seems dark . Due to the structure of the polar bear hairs can sometimes " go green ." It happens in a hot climate ( in zoos ) , when inside hairs infest microscopic algae .Soles of the feet are hit wool, not to slip on the ice and not freeze. Between the fingers has a flipper and the front paws trimmed stiff bristles. Large claws can keep even a strong prey.