Why Don't Penguin Feet Freeze?

Standing barefoot on a glacier, human feet would freeze solid -- but penguin feet are fine. Learn why in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain stuff from how stuff works. Hey, brain stuff,
Lauren Vogel bomb here. How long could you stand on
Antarctic ice before your bare feet froze solid? A minute?
Maybe two? If you're an emperor penguin, you can do
it for two months, and in wind chills as low
as negative seventy five degrees fahrenheit that's about negative sixty

(00:22):
degrees celsius. Those naked bird feet may look positively frigid,
but their special circulation acts as a kind of anti
freeze to keep them just warm enough in environments where
we would get frost bite immediately. Penguins are adapted just
for cold temperatures. They have specialized super insulating feathers that
keep heat in. We humans would get frost bite in

(00:42):
penguins place, specifically because our bodies are adapted to a
wider range of temperatures. To keep our internal body temperature
right around in ninety eight degrees. In the heat and
the cold, the blood vessels inner skin expand or contract
to direct or restrict the flow of blood out to
our skin. Our organs stopped working. Some were above a
hundred and four degrees fahrenheit that's about forty degrees celsius.

(01:03):
So when we get warm, our blood vessels dilate to
circulate more warm blood to the skin, where hopefully that
heat transfers out into the environment. A sweating can help
with this, but our organs also stop working somewhere below
ninety degrees fahrenheit that's about thirty two degrees celsius. So
when we get cold, most of our blood vessels constrict
to limit the amount of warm blood going too the

(01:24):
skin where it would lose more heat, and thus keep
that warmth circulating in our core areas. Our hands, feet,
and limbs in particular are full of these tiny blood
vessels that can either warm up or chill off fast.
Your hands may even appear paler during exposure to freezing
weather because there's less blood in them. It's been redirected
to the core of your body to make sure those
vital organs stay warm. But penguin legs and feet have

(01:48):
evolved specifically to lose as little heat as possible. Penguin
feet hold onto heat by restricting blood flow in really
cold weather, keeping foot temperature just above freezing. Penguin legs
work like a heat ex change system. Blood 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

(02:09):
the body. Feet get cool blood, so there's less heat
to lose while the body stays toasty. This special ability
is part of how penguins keep their eggs warm until
they hatch. Male emperor penguins incubate a single egg on
top of their feet for two months in the dark
of winter while females are out feeding at sea. They
also cover the egg with a flap of warm belly

(02:29):
skin called a brood pouch to keep it out of
the elements, and nurturing doesn't stop there for these dedicated dads.
If females haven't returned with food by the time the
chicks hatch, male emperors feed their babies for a few
days on a kind of milk made from special cells
inside their throats. Today's episode was written by Lori and

(02:51):
Fick and produced by Tyler Clang for iHeart Media and
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