Polar Bear adaptation to the cold and hostile Arctic climate is one of nature's wonders. The ever-changing sea ice, where polar bear live, is one of the cruelest and most relentless climates on the globe.
It's only in modern evolutionary cycle that bears adjusted to arctic sea life. It started during the Ice Age, in the northern seas, when the seals needed to breathe and reproduce near the water's surface. Because of this, the seals placed a copious year-round food source within reach of a population of brown bears, who then set out to inhabit the ice, changing into something akin to the polar bear of today, around 100,000 years ago.
Weighing about 330 to 1,760 pounds, the length of the polar bear's body is approximately 6.6 to 10 feet. The male body is generally larger than the female. The polar bear, like to the brown bear, is big and stocky. It has an long neck and small head. Its fur, normally white, sometimes appears yellow, due to oxidation.
A polar bear has black skin, which assists it's adjustment to the Arctic temperature, absorbing and holding heat from the sunlight. It is unquestionably well clad for the weather with a layer of fat more than 4 inches thick, supplying efficient insulation. The heavy fur on its feet (its foot is about 9 inches wide and 12 inches long) provides warmth and traction. As each foot is so large, it acts as a practical snowshoe.
It adjusts well to swimming with its broad feet that serve as paddles and when swimming underwater it lays the tiny ears flat for protection, and its nostrils close under water. It paddles at about 6 and one-half miles per hour --paws only, hind paws trailing--and can remain submerged for about 2 minutes. The hairs of its waterproof coat are hollow which is an effective insulator and increases the bear's buoyancy while swimming.
A polar bear has a good sense of smell, sensing prey at a distance of about 20 miles. While little is known about its sense of touch (its eyesight and hearing is acute), a polar bear is able to manipulate assorted objects with surprising dexterity.
With canine teeth larger and malariform teeth sharper than those of other bears, the polar bear is the most carnivorous North American bear.
A polar bear lives on Arctic islands, sea ice, and water and continental coastlines. It favors the sea ice habitat, with water channels or cracks through the ice, next to continental coastlines or islands. Many polar bears spend part of the year on land, although in warmer climates a bear might become stranded. Most pregnant females spend the autumn and winter on land in maternity dens.
A polar bear travels throughout the year within individual home ranges, which tend to be a larger area than for other mammal species because of the changes in sea ice from year to year and even season to season. Small home ranges (19,000 to 23,000 miles) can be found near Canadian Arctic Islands, while bigger home ranges can be found in the Bering or Chukchi Sea areas. The polar bear remains in the same area during the same season. A polar bear is capable of traveling 19 miles or more per day for several days, although some are capable of a good deal more than that. One can only hope that polar bear adaptation will continue, as their habitat area shrinks and the pressures of civilization continue to encroach on the the natural homes where the polar bear dwell.
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