The polar bear (Ursus maritimus) is a bear native to the Arctic and Subarctic. The world's largest land carnivore, an adult male polar bear generally weighs 300–600&160;kg (660–1320&_160;lb), while an adult female polar bear is about half that size. Its fur is hollow and translucent, but usually appears as white or cream colored, thus providing the animal with effective camouflage, though its skin is actually black. Its thick blubber and fur insulate it against the cold. The bear has a short tail and small ears that help reduce heat loss, as well as a relatively small head and long, tapered body to streamline it for swimming.
A semi-aquatic marine mammal, the polar bear is adapted for a life on land, sea, and ice,and is the apex predator within its range. It feeds mainly on seals, young walruses, and whales, although it is an opportunistic feeder and will eat almost anything if hungry.
The polar bear is classified as a vulnerable species. Some zoologists and climatologists believe that the projected decreases in the polar sea ice due to global warming will reduce their population by two thirds by 2050.Long-term studies show that 7 of the 19 recognized subpopulations are declining or are already severely reduced, 8 are stable, increasing or not reduced, and 7 do not have sufficient data to make a determination.The U.S. Fish and Wildlife Service formally proposed listing the polar bear as a threatened species on January 9, 2007. A final decision was due on January 9, 2008 but has been delayed.