BrainStuff Classics: 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 classic episode of BrainStuff, based on this article: https://animals.howstuffworks.com/mammals/why-penguin-feet-dont-freeze.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to Brainstuff, a production of iHeartRadio. Hey brain Stuff,
I'm Lorn vogel Bomb, and this is a classic episode
from our archives. We've talked before on the show about
how various cold blooded animals survive the winter, but in
this one we shift our focus to birds clearly designed
to cope with cold weather. Penguins. Their bodies are well insulated,

(00:26):
but how do their little feet not freeze? 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 windchills as low as
negative seventy five degrees fahrenheit that's about negative sixty degrees celsius.

(00:48):
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'd get
frostbite immediately. Penguins are adapt to just for cold temperatures.
They have specialized super insulating feathers that keep heat in.
We humans would get frostbite, and penguins place specifically because

(01:08):
our bodies are adapted to a wider range of temperatures
to keep our internal body temperature right around ninety eight degrees.
In the heat and the cold, the blood vessels in
our skin expand or contract to direct or restrict the
flow of blood out to our skin. Our organs stop
working somewhere above one hundred and four degrees fahrenheit that's
about forty degrees celsius. So when we get warm, our

(01:29):
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 to the skin where it would lose more heat,

(01:51):
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

(02:12):
and feet have 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 exchange 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

(02:33):
returns to 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

(02:53):
belly 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 is based on

(03:15):
the article why Penguin feet don't freeze on how stuffworks
dot Com, written by Lorraine fifth Rain. Stuff is production
of iHeartRadio in partnership with HowStuffWorks dot Com and is
produced by Tyler Klang. Four more podcasts from my heart Radio,
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