How long could you stand on Antarctic ice before your bare feet froze solid? A minute, maybe two?
If you are an emperor penguin, you can do it for two months, and in wind chills as low as -75 degrees Fahrenheit.
Those naked bird feet may look positively frigid, but their special circulation acts as a kind of antifreeze to keep them just warm enough that they do not freeze.
Penguin legs and feet have evolved to lose as little heat as possible.
Penguin feet hold onto heat by restricting blood flow in really cold winter, keeping foot temperature just above freezing.
Penguin legs work like a heat exchange system; bolld vessels to and from the feet are very narrow and woven closely together, cooling the blood from the body on the way to the feet and heating the blood as it returns to the body. Feet get cool blood so there is less heat to lose, while the body stays toasty.
This special ability is part of how penguins keep their eggs warm until they hatch.
Humans have the ability to restrict blood flow to their extremities in cold weather too, although not as dramatically as penguins.
Your hands get whiter during freezing weather becasue there is less blood in them-it is been redirected to the core of your body to make sure vital organs stay warm.
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