The Arctic is a cold region, with temperatures sometimes dropping to -80 degrees Fahrenheit during winter. The animals who survive and thrive in this area have specific adaptations to maintain their body temperatures. These adaptations range from blubber to different blood vessels than mammals in more temperate climates.
Some Arctic mammals spend their lives in and out of the water. Polar bears must keep warm on land and when swimming in the water. They are large animals, and the increased number of cells helps to produce more heat. Their limbs are shorter, limiting heat loss from exposed surface area.
Blubber is a layer of fat and oil possessed by some Arctic mammals. Animals with blubber are better able to conserve heat, and mammals such as seals and whales have a large amount. They even have more than polar bears, likely attributing to the fact that they spend more -- or all of -- their time in the water. Blubber also helps marine mammals remain buoyant in the water. The layer is thicker in colder regions and thinner in warm climates. Animals with blubber also can have increasingly fatty milk, which helps young animals put blubber on faster. Polar bears have the fattiest milk of any bear, with a reported 35.8 percent fat content.
Hair and Skin
Arctic animals with hair often have hollow hair shafts. Combined with a thick coat of fur, these hairs trap warm air near the body, conserving heat. Some of these mammals -- such as polar bears -- also have dark skin, which allows heat absorption when the skin absorbs UV light. Animals that spend part of their time on land, such as seals and polar bears, also have white fur, which helps camouflage the creatures.
Marine Arctic animals have extra blood vessels. Their blood vessels exist between the skin and blubber and under the blubber layer. Blood can be shunted away from the skin, allowing these animals to keep their blood warm when the water is cold. Blood can be shunted back to the skin as the animal warms up due to activity or the surrounding water temperature elevating. Marine mammals also have counter-current heat exchange in their blood vessels, where each artery is surrounded by multiple veins. As warm blood leaves the heart to go to the fins or extremities via the arteries, heat is passed to the colder blood carried in the veins from the extremities back to the heart. Scientists even noted that gray whales have this system present in the vessels in their tongues, which they constantly expose to cold waters as they consume krill.
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Elizabeth Muirhead is a practicing veterinarian with an undergraduate degree in biological sciences. She has real-world experience with the husbandry, grooming, training and feeding a variety of household pets.