WEBVTT - BrainStuff Classics: Why Don't Penguin Feet Freeze?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio. Hey brain Stuff,

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<v Speaker 1>I'm Lorn vogel Bomb, and this is a classic episode

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<v Speaker 1>from our archives. We've talked before on the show about

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<v Speaker 1>how various cold blooded animals survive the winter, but in

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<v Speaker 1>this one we shift our focus to birds clearly designed

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<v Speaker 1>to cope with cold weather. Penguins. Their bodies are well insulated,

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<v Speaker 1>but how do their little feet not freeze? Hey brain stuff,

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<v Speaker 1>Lauren vogel Bomb here, how long could you stand on

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<v Speaker 1>Antarctic ice before your bare feet froze solid? A minute?

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<v Speaker 1>Maybe two? If you're an emperor penguin, you can do

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<v Speaker 1>it for two months, and in windchills as low as

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<v Speaker 1>negative seventy five degrees fahrenheit that's about negative sixty degrees celsius.

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<v Speaker 1>Those naked bird feet may look positively frigid, but their

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<v Speaker 1>special circulation acts as a kind of anti freeze to

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<v Speaker 1>keep them just warm enough in environments where we'd get

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<v Speaker 1>frostbite immediately. Penguins are adapt to just for cold temperatures.

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<v Speaker 1>They have specialized super insulating feathers that keep heat in.

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<v Speaker 1>We humans would get frostbite, and penguins place specifically because

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<v Speaker 1>our bodies are adapted to a wider range of temperatures

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<v Speaker 1>to keep our internal body temperature right around ninety eight degrees.

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<v Speaker 1>In the heat and the cold, the blood vessels in

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<v Speaker 1>our skin expand or contract to direct or restrict the

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<v Speaker 1>flow of blood out to our skin. Our organs stop

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<v Speaker 1>working somewhere above one hundred and four degrees fahrenheit that's

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<v Speaker 1>about forty degrees celsius. So when we get warm, our

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<v Speaker 1>blood vessels dilate to circulate more warm blood to the skin,

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<v Speaker 1>where hopefully that heat transfers out into the environment. A

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<v Speaker 1>sweating can help with this, but our organs also stop

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<v Speaker 1>working somewhere below ninety degrees fahrenheit that's about thirty two

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<v Speaker 1>degrees celsius. So when we get cold, most of our

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<v Speaker 1>blood vessels constrict to limit the amount of warm blood

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<v Speaker 1>going to the skin where it would lose more heat,

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<v Speaker 1>and thus keep that warmth circulating in our core areas.

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<v Speaker 1>Our hands, feet, and limbs in particular are full of

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<v Speaker 1>these tiny blood vessels that can either warm up or

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<v Speaker 1>chill off fast. Your hands may even appear paler during

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<v Speaker 1>exposure to freezing weather because there's less blood in them.

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<v Speaker 1>It's been redirected to the core of your body to

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<v Speaker 1>make sure those vital organs stay warm, but penguin legs

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<v Speaker 1>and feet have evolved specifically to lose as little heat

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<v Speaker 1>as possible. Penguin feet hold onto heat by restricting blood

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<v Speaker 1>flow in really cold weather, keeping foot temperature just above freezing.

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<v Speaker 1>Penguin legs work like a heat exchange system. Blood vessels

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<v Speaker 1>to and from the feet are very narrow and woven

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<v Speaker 1>closely together, cooling the blood from the body on the

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<v Speaker 1>way to the feet and heating the blood as it

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<v Speaker 1>returns to the body. Feet get cool blood, so there's

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<v Speaker 1>less heat to lose while the body stays toasty. This

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<v Speaker 1>special ability is part of how penguins keep their eggs

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<v Speaker 1>warm until they hatch. Male emperor penguins incubate a single

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<v Speaker 1>egg on top of their feet for two months in

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<v Speaker 1>the dark of winter while females are out feeding at sea.

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<v Speaker 1>They also cover the egg with a flap of warm

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<v Speaker 1>belly skin called a brood pouch to keep it out

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<v Speaker 1>of the elements, and nurturing doesn't stop there for these

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<v Speaker 1>dedicated dads. If females haven't returned with food by the

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<v Speaker 1>time the chicks hatch, male emperors feed their babies for

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<v Speaker 1>a few days on a kind of milk made from

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<v Speaker 1>special cells inside their throats. Today's episode is based on

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<v Speaker 1>the article why Penguin feet don't freeze on how stuffworks

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<v Speaker 1>dot Com, written by Lorraine fifth Rain. Stuff is production

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<v Speaker 1>of iHeartRadio in partnership with HowStuffWorks dot Com and is

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<v Speaker 1>produced by Tyler Klang. Four more podcasts from my heart Radio,

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