Cold-Weather Adaptations
Understand how body features and behaviors help polar animals survive. Blubber slows heat loss in seals, whales and walruses. Dense fur traps air near a polar bear's skin. Heat exchange between nearby blood vessels reduces heat loss in penguins. Many Arctic foxes have white winter coats for camouflage, and some birds migrate to find food.
What a learner can do afterwards
- Describe at least three adaptations, such as blubber, dense fur, heat-saving blood flow, winter coats or migration
- Explain the purpose of each adaptation (e.g. blubber insulates against cold water, white fur provides camouflage in snow)
- Use adaptation to mean a body feature or usual behavior that helps an animal survive in its environment
1 · Read
You know some polar animals already. An adaptation is a body feature or usual behavior that helps an animal survive where it lives. Animals use different adaptations. Seals have blubber, bears have dense fur, and some birds migrate.
Seals, whales and walruses have blubber, a thick layer of fat under the skin. It slows the loss of body heat to cold water. This is insulation. An insulating layer helps an animal keep heat its body makes. It does not make heat or stop every bit of heat from escaping.
A polar bear's dense underfur traps air near its skin. The fur and trapped air slow heat loss. The coat's pale color helps the bear blend into snow, but color does not make heat. Fur and blubber help the bear keep body heat.
In a penguin's feet, nearby blood vessels carry blood in opposite directions. Warm blood going toward the feet gives some heat to cooler blood returning to the body. Outgoing blood becomes cooler; returning blood becomes warmer. This reduces heat loss and helps keep the body's center warm. It is called countercurrent heat exchange.
Arctic foxes grow thicker winter coats. Many have white winter fur that helps them hide in snow; others have darker winter coats. Thickness helps with warmth. Color helps with camouflage, or being hard to see. Some Arctic birds migrate between seasonal homes to find food and open water in winter.
Blubber and dense fur slow heat loss. Penguins save heat through blood flow. Fox coats help with warmth and camouflage. Some birds migrate to find food.
Three original readings written for this dataset. Linked TED-Ed videos by Nadia Frontier and Charles Wallace.
More to read
Thickness and color do different jobs
An Arctic fox grows a thicker coat for winter. The extra fur slows heat loss from its warm body to the cold surroundings.
Many Arctic foxes also have white winter fur. Against snow, white fur makes them harder to see. This is camouflage. Other Arctic foxes have darker winter coats, so white is not a rule for every fox.
Separate the coat's two jobs. Thickness helps with keeping body heat. A color that matches the surroundings helps with hiding.
Making heat and saving heat
Birds and mammals make heat inside their bodies. Shivering adds heat because muscles are working. An insulating coat has another job: it slows heat leaving the body.
Blood flow can help save heat too. Nearby vessels can carry warmer blood outward and cooler blood inward. Heat passes from the warmer blood to the cooler blood. Returning blood gains heat before reaching the body's center. Outgoing blood becomes cooler, reducing heat lost at the exposed body part.
Animals can also change their behavior. Penguin chicks may huddle, leaving less of each chick exposed to cold surroundings.
Slowing heat loss
Heat moves from warmer places toward cooler places. A warm animal in cold surroundings loses some heat even while its body makes more.
Insulation slows that loss. Dense fur holds air near the skin. Blubber is a fat layer under the skin that also slows heat transfer. Both help polar animals keep body heat.
Neither layer stops every bit of heat from escaping. The animal still needs food to supply energy for its body. Keeping heat and making heat are different jobs.
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