Zoology

Evolution of the Polar Bear



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Evolution of the Polar Bear

It is believed by zoologists, that the polar bear evolved from a species of brown bears in Siberia, making polar bears the eight species of bears in the world.

With the shifting of polar ice caps and glaciers, the brown bear species that was native to that area were forced to adapt to their new environment, undergoing physical body changes to keep warm in the brutally cold weather. Their fur thickened and eventually turned white. Over time, the next few generations of polar bears, evolved with even thicker fur, a more rounded pointy face, larger teeth and claws, bigger feet with a patch on the bottom to help them keep their grip, when walking on the ice and sharper senses.

Today, polar bears live in the Arctic, Alaska, Greenland, Canada and Norway.
Their habitat is snow covered mountains, large mostly frozen bodies of water and where seals are plentiful. Besides seals, polar bears eat walrus's and even whales. The snow helps them to blend into their environment for safety, even though the only predator they have is man.

Adult male polar bears grow to weight 600 to 1500 pounds. Female polar bears weight between 250 and 700 pounds. Their lifespan is the wild is 15 years and in captivity it is usually 30 years, sometimes longer.

Polar bears do not hibernate, they have no reason to, as they are accustomed to the cold weather and they have plenty of food available year round.

Female polar bears are mature enough to reproduce at 5 years old, usually only having one or two cubs at a time. The mother polar bears, make a den in the snow, to "hibernate" during the gestation period. They mate in April and the cubs are born in December. The mother and cubs stay in the den until spring. The cubs only way a pound and are a foot long at birth, when they emerge from the den they weight between 20 and 25 pounds. The mother never leaves the den. She doesn't eat at all during that time. The cubs will stay with their mother for 2 years before going off on their own.

There are a few dozen polar bears in zoo's all over the world. They are huge, beautiful animals and thrive well in captivity.

Source
www.polarbear.org

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