The polar bear (Ursus maritimus) is a bear native largely within the Arctic circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak bear, which is approximately the same size. An adult male weighs around 350–680 kg (770–1,500 lb), while an adult female is about half that size. Although it is closely related to the brown bear, it has evolved to occupy a narrow ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice, and open water, and for hunting the seals which make up most of its diet. Although most polar bears are born on land, they spend most of their time at sea (hence their scientific name meaning "maritime bear") and can hunt consistently only from sea ice, so spend much of the year on the frozen sea.
Polar bears can be found in Northern Canada, Alaska, Greenland, Norway, and Russia.
There are believed to be at least 22,000 polar bears worldwide, about 60% in Canada.
Polar bears have no natural predators and top the arctic food chain. They are carnivores and their diet is primarily ringed seal but polar bears will sometimes eat walrus, whales, or any other available meat when necessary.
Polar bears are the largest land carnivore. Adult polar bears measure 8 to 10 feet tall and weigh between 550 to 1,700 pounds. Adult females measure 6 to 8 feet tall and can weigh 200 to 700 pounds.
In the wild, polar bears usually live 15 to 18 years, but can live into their early 30s. The oldest polar bear in captivity (in a London zoo) lived to be 41.
The scientific name of polar bears, ursus maritimus, translates to "sea bear."
Polar bears mate in spring, and males and females only stay together for a short period of time. Females feed heavily in late summer, then in the fall dig a snow den in which to give birth. The mother bear, living off fat reserves, and the cubs, growing rapidly from their mother's high-fat milk, remain in the maternity den until spring. Polar bear cubs typically stay with their mother for 2 1/2 years.
Polar bears are so well-adapted to the cold that even in very cold weather, they are more likely to overheat than freeze. They generally walk instead of run to keep from overheating.
Polar bears are excellent swimmers. They use their front paws like paddles and their hind legs like rudders to move through the water.
The fur of polar bears is not white, in fact, it is transparent and has no pigment at all. The reflection of light creates the white or off-white appearance. Underneath their fur, polar bears have black skin.
Polar bears enjoy naps.
An international Agreement on the Conservation of Polar Bears was signed by the governments of Canada, Denmark, Norway, the USSR, and the United States in November 1973.