Cold Feet: Why Don’t Penguin’s Feet Freeze?
by Sian Liversage
We all know that penguins endure and survive freezing temperatures in the Antarctic, these can range as low as -70˚C in the centre to -20 ˚C around the coast. Their bodies stay warm due to their insulating layers of blubber which lies just beneath the skin. However, their webbed feet are continually in contact with snow and ice, and yet somehow they manage to stay free from frostbite. So, it begs the question: Why don’t their feet freeze?
Penguins have special adaptations to keep their feet from freezing
Like many other species around the world, penguins have adaptations to avoid losing too much heat and to preserve a central body temperature. Penguin feet make it problematic to maintain that perfect body temperature of 40°C since they are constantly exposed to the elements; their feet cannot be covered with blubber or feathers like their bodies are, and together they create a large surface area exposed to the cold. But they need their feet so they can walk around the icy surface without slipping, and also so they can steer themselves when swimming.
A variety of penguins have developed behaviours that enable them to keep their feet warm. For example, Emperor Penguins hunch down so their bellies and feathers cover their legs, and they also rock back and forth onto their heels to lift their feet off the ice, therefore reducing contact time on the ground.
Penguins keep their feet from freezing not only behaviourally, but also through internal mechanisms
This is not the only way penguins avoid getting cold, however. They have evolved remarkable physical attributes too that make them perfectly adapted to their environment. There are two hidden mechanisms going on inside those legs and feet.
First, a penguin can control the rate of blood flow to the feet by varying the diameter of arterial vessels supplying the blood. During cold conditions, the flow of blood is reduced to hold onto heat. In winter, penguins will keep their feet a degree or two above freezing which reduces the chance of heat loss and avoids getting frostbite.
And, of course, not all penguins live in places where their feet get cold
Not all penguin species live in freezing conditions though. Some species like Galapagos Penguins live in scorching sun and heat and thankfully their specialised heat exchange system also serves as a vital outlet for when their bodies become too warm. Blood vessels in the penguin’s feet expand, doing the opposite of what they do when they are cold. This allows an increase in blood flow, which in turn enables heat loss from the body. You may see penguins lying on the ground with their feet in the air and their flippers out to the sides to speed this process up and get rid of excess body heat.
Humans can also do what penguins do with their feet (to some extent)
Amazingly, humans can also restrict blood flow to their extremities too. Our hands and feet will go white when they are freezing due to less blood circulating to them; blood is being redirected and prioritised to go to the core of the body where the vital organs will be kept warm. On the other hand, when we are warm our hands and feet will turn pink which is our body trying to cool us down. Controlling blood flow is very sophisticated and involves the hypothalamus, the nervous system and endocrine systems all working together to function properly.
Secondly, penguin legs work like a heat exchange system; blood vessels to and from the feet are narrow and woven closely together, which cools the blood from the body on the way to the feet and vice versa when the blood returns to the body. Therefore, their feet receive cool blood instead of warm blood, as this means less heat is lost while the body continues to maintain that toasty 40°C.
These adaptations show just how truly extraordinary penguins are; generations have survived the worst conditions nature could throw at them. These cold-adapted species live a challenging life, walking 100s of kilometres to feeding grounds, surviving snowstorms, and standing for weeks on ice while incubating an egg, and at the same time maintaining a warm body core temperature. Despite all these potential setbacks, their incredible feet and overall mechanisms to survive are still yet to be hindered by Mother Nature.
Penguins are amazing birds that have adapted ways to live in extreme environments. Have you ever seen some of these penguins in the wild? Tell us about it in the comments below. And please assist with our conservation projects and help us continue to provide you this information by donating to Penguins International.
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- Encyclopedia Britannica Blog. 2011. Penguin Feet: Avoiding Frostbite in the Antarctic. Webpage: http://blogs.britannica.com/2011/01/penguin-feet-avoiding-frostbite-in-the-antarctic/
- How Stuff Works. 2019. Why Penguin Feet Don’t Freeze. Webpage: https://animals.howstuffworks.com/mammals/why-penguin-feet-dont-freeze.htm
- New Scientist. 2006. Why don’t penguins’ feet freeze? And 114 other questions. P. 47-77