Most penguins live in the Antarctic and Sub-Antarctic. They swim for hours at a time in frigid ocean water. Many sit on nests incubating eggs as snow falls around them, and the Emperor Penguins lay eggs in the winter, incubating them on their feet, day after day, through the coldest winter on Earth. How do penguins keep warm and keep eggs from freezing?
All penguins, and many other birds, have a blood circulatory arrangement whereby the arterial blood flowing to the feet is cooled by venous blood returning to the body. This keeps the feet much cooler than the core temperature of the body and prevents a great deal of heat from being lost through exposed feet. Penguins also have lots of feathers and fat to keep them warm.
Emperor Penguins
The Emperor Penguin is the undisputed penguin master of staying warm. These birds lay eggs in the bitter cold of the Antarctic winter and incubate them on their feet under folds of skin and feathers through the winter. Emperor penguins have a number of ways to conserve body heat and keep the eggs warm, even at temperatures of -40°C:
- As in other bird species - but even more efficient - blood flowing to the feet and flippers, and other areas close to the skin, passes next to returning blood. Body heat is transferred from arterial blood to returning blood to minimize heat loss.
- The Emperor Penguin's flippers and bill are relatively small, compared to other penguins, and their thick solid bodies have minimal surface area exposed to the elements.
- Air drawn in by breathing is warmed in the same way as blood returning from the flippers and feet – cold air coming in is warmed by hot breath going out.
- Layers of dense, warm feathers cover the penguins’ bodies and blanket legs, feet and eggs (Eggs are kept at a cozy 33°C, even when it is -40°C outside!).
- Emperor Penguins are able to build up extensive fat reserves in their cylindrical bodies, and have a fat layer insulating their inner core—an important feature that gets them through periods of extreme cold and stretches between feeding.
- Emperor Penguins huddle together for warmth, with those on the outside of the huddle being cycled through to the inside and then back to the edge so they don’t spend too long at the exposed periphery.
Tropical Penguins
Some penguins do live and nest in warm places compared to the Emperor Penguin. Penguin species that have to deal with warmer temperatures sometimes need to get rid of heat rather than conserve it. These species have larger flippers and areas of exposed skin on the face to allow heat to escape. It’s also normal for them to live in burrows to escape surface heat.
Sources
Christopher Perrins, ed. Firefly Encyclopedia of Birds. New York: Firefly. 2003
US Fish and Wildlife Service, Chesapeake Bay Field Office. “How Birds Stand the Chill.”
Sea Fisheries Institute in Gdynia: Gdynia Aquarium.
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Rosemary Drisdelle - Rosemary Drisdelle has been published many times as a nonfiction writer and several times as a poet. Her first book, Parasites: Tales of ...
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