The polar bear is a carnivorous bear whose native range lies within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and land masses.

It is a large bear, about the same size as the omnivorous Kodiak bear (Ursus arctos middendorffi) A boar (male) weighs about 350-700 kilogram -1440 lbs and a sow (female) about 150 to 350 kilos - 875 lbs. Although it is a sister species of the brown bear, it has evolved to occupy a narrower ecological niche with a body adapted for cold temperatures, moving across snow, ice and open water, for hunting seals which make up for most of it's diet and though born inland spend most of their time on the sea ice.Polar bears hunt their preferred food of seals from the edge of the sea ice, and often live off their fat reserves when there is no ice present.

The polar bear's fur isn't white, each hair is a hollow tube, they look white because the hollow hairs reflect the light and on sunny days trap the sun's infrared heat and keeps the bear warm. The fur is also oily and water repellant and does not mat when wet. Underneath the fur, a polar bear's skin is black and this helps it to absorb the sun's heat and stay warm.They also have a 4 inch layer if fat under the skin, this prevents them from losing heat.

They are classified as marine mammals. Man is their only predator and his advances in civilization has encroached upon the habitat of these bears whose numbers are growing less every day and make it a vulnerable species.

More Info: en.wikipedia.org