The polar bear is considered to be a relative newcomer in the animal kingdom, having evolved from a form of brown bears. Bears originated in Eurasia and moved in waves to the Americas via the isthmus that in the past connected Asia and Alaska. It is now the Bering Straight. In the first wave were the spectacled bears which became extinct. The second wave brought the black bear and the third the brown bear. It is a form of the brown bear that the polar bear evolved from. Over a long period of time as these bears migrated north into colder areas the polar bear that we know today, emerged.
The polar bear is the largest carnivore in the world and is considered to be semiaquatic. Its fur color evolved to help it blend in with its habitat when hunting. It does not need camouflage for its enemies - it has none other than man!! Another adaptation is its head size. A polar bear's eyes are set close together and face straight ahead giving it good vision and ability to judge distance. It also has small ears. These features help prevent heat loss which is extrememly important in the harsh climate in which it lives. They have 42 teeth for chewing although they sometimes use them to intimidate other animals. The thick coat of fur helps to keep them warm and dry. The fur is made up of hairs that are clear and hollow. But sunlight reflects off these hairs making the animals appear to be white or yellow. The clear, hollow hair allows the sun's rays to reach the body of the bear. The black skin of the bear absorbs the heat and protects the bear from the cold. The fur is slightly oily which helps to separate the hairs when wet allowing for quick drying. A bear can shake off extra water preventing ice from forming. Polar bears have a thick layer of blubber under the fur which helps to insulate the bear. When food is scarce, a polar bear's body will burn this fat for energy. Polar bear paws are large - measuring up to a foot across! Each foot has five toes and five sharp claws. The footpads, claws and fur help the bear walk on ice. Their feet are partially webbed to help them swim.
Polar bears are solitary creatures. Males and females only get together to mate. Although when they do come across another bear they will fight or play. This doesn't last long because they get too warm and have to cool down! Female polar bears will den up to give birth to their babies. She usually has two cubs between November and January. Newborn cubs weigh less than 2 pounds, have little fur, cannot hear and will not open their eyes until they are about 33 days old. They nurse from her rich (30% fat) milk. Yet, at only 2 months of age they are furry miniatures of their momma bear! She is solely responisble for raising the cubs. A female bear usually doen't eat when in the den which means she can go 6 - 8 months without food. In order to be able to do this, she must put on 400 pounds of fat prior to going into the den. More than half of all polar bear cubs do not survive their first year. Some die from starvation, accidents or are eaten by other bears. If a polar bear cub makes it to two years of age, it may live a long time.
Contrary to popular belief, polar bears don't really hibernate. Pregnant females will den-up to have their babies but a sleeping polar bear will rise instantly and ready to fight to protect her cubs at the slightest sound. When food is scarce and winter is particularly harsh, other bears will den up too. But typically, they wander on the ice hunting seals all winter long.
Cute alert!!! See a mother and her cubs emerge from their den: "http://www.youtube.com/embed/OwZH_aT0FGI"
They are expert hunters! Although they will eat harp, hooded and bearded seals, ringed seals are their main winter diet. Other seals and larger prey can injure a bear. Seals can stay under water for a long time but eventually they must surface for air. Polar bears use their keen sense of smell to locate seal breathing holes in the ice. They will wait for hours if necessary for the seal to surface. When it does, the bear strikes it with its front paw and grabs it with its teeth. Polar bears are strong enough to pull a 200 pound seal through the ice hole in one swift movement.
Cute alert!!! See polar bears playing with dogs!!
