How Do Polar Bears Adapt to Their Environment?

By Randy Green

Most everyone knows that polar bears are acclimatized to cold. Life in the Arctic is harsh even in the very best of times. But here are one or two polar bear facts that explain modifications you may not have known about.

Polar bear adaptions to arctic conditions extend to water as well. Polar bears are excellent swimmers and can swim for long distances in water terribly near the freezing level. In fact they have been seen swimming in open water, long distances from any shore. Their ease in swimming in the water and on the sea ice has led to them being classified as a marine mammal, just as seals, dolphins and whales are, for legal protection purposes. They are guarded in the US under the Marine Mammal Protection Act.

One biologist even described polar bears as a transitory animal in the act of developing from a land animal to a sea animal. Naturally, one can’t know where the evolution of a species will finish up, but it’s an good outline of a species that has made major adaptations to a marine habitat.

Among other polar bear modifications to the far north is the yellow-white coat, coupled with a black skin and hollow fur. The bears ‘ coat colour definitely acts to camouflage it when on the ice. Anyone who has spent any time in the Arctic with polar bears will tell you tales of looking right at a pale object and not having the ability to tell if it's a bear till it moves. The hollow fur essentially acts to transmit the dim Arctic daylight (sort of like a fiber optic thread conducts light) to the dark skin where it is absorbed as heat. One or two inches of skin fat in a healthy bear also act as insulation against the frigid winter and cold sea water as well as storage of energy for their long periods of fasting in the summer months.

Polar bear adaptions to the harsh Arctic conditions reaches to the way they bear their cubs. Females generally mate on the ice during the early spring. If her eggs are successfully fertilized, she delays implanting of the zygote in her uterus until she can successfully den when the snow falls in the fall. She then carries her pregnancy to term through the winter, safe in her den.

In spring, typically March, the Arctic is still snow-bound and frozen, but the female emerges from her den with her cubs, ranging from one to three cubs (two is average). These little cubs of the year (COY) are tiny and weak, but since all of the other non-breeding bears are far out on the sea ice hunting for seal, the mother does not have to worry about her cubs being harmed. She will then take the cubs out onto the sea ice for what is usually her first meal in up to seven or 8 months! This is an important period for both her and her cubs: if she is not in a position to catch enough seal to eat, her cubs and even herself may not survive.

Randy Green is an originator of the Churchill polar bear trips that have become terrifically acclaimed among wildlife fans in recent times. His site covers all aspects of planning a polar bear trip to Churchill.

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Topics: Environment | Comments Off

Tags: Environment, polar bear facts, polar bears

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