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Physical Characteristics of the Polar Bear
Polar Bear (Ursus maritimus):
- an adult male weighs around 360 to 680 kg, while the female can weigh half as much as the male
- adult male ~2.6m
- adule female ~2m
- arctic sea ice
- primary prey ringed and bearded seals
- secondary prey walrus and baluga whales
- mature polar bears tend to consume the calorie rich skin and bladder of the seals
- young polar bears usually eat the protein rich red meat
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Polar Bear Adaptations to Cold
In many ways, polar bear adapted to cold by using the old fashion methods, through thick layer of fat and fur. However, polar bears have made some improvement in both of these features. A mature polar bear can have up to 10 cm (3.9 in.) of blubber, which is a thick layer of vascularized fat, found under the skin. Blubber serves as an important function in polar bear adaptation to cold. It is a lipid rich fat that is found on many sea mammals. It is not only an excellent insulator, but also an area to store reserved energy. This lipid rich fat gives the polar bear the ability to swim in the cold water of arctic sea ice, because although water reduces heat retaining capacity, lipids increase it.
The second powerful factor that is essential in polar bear adaptation to cold is their fur. The polar bear has unique "hollow guarded fur" to protect them from the cold. Its fur consists of two layers, the heavy under fur layer and the outer layer guard hair. The outer layer fur has a whitish tan color, but in fact it is actually transparent. Scientists once thought that the transparent hollow guarded fur was similar to fiber optic tubes, which direct sunlight into bear's darker skin to absorb heat, but that theory has been disproved by recent studies.
Furthermore, the small ear and tail also play important roles in polar bear adaptations to cold. When comparing polar bears with brown bears, notice that the polar bear has a significantly smaller ear and tail. These adaptations allow them to retain heat. By keeping them closer to the body, a polar bear uses less energy to keep them warm.
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A Victim of Its Own Success?
While polar bear adaptations to cold have benefited them greatly in the arctic sea ice environment, the drastic climate change significantly impacted their habitat and their survival. There is a down side to polar bear adaptations to cold; that is -over heating. Polar bears overheat at a relatively cold temperature, 10 °C (50 °F). The climate change, which causes the overall warming in the arctic region and the reduction of arctic sea ice, will have negative impact on polar bears. The reduction of the polar bear habitat would cause the population to decrease. According to the World Conservation Union, there is a "suspected population reduction of >30% within three generations (45 years)."
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Understanding the polar bear adaptations to cold can help give insights to why polar bear population will be reduced in the coming years with the drastic climate changes. It is very important for us to keep the earth a livable environment for all of us, human and animals alike.
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