iD magazine



Warning: If you try to lick a frozen surface, your tongue will get stuck. The reason: The warmth of your tongue briefly melts the surface of the ice before it freezes again, thereby freezing the moisture on your tongue to the object. So why doesn’t that happen to ducks when they’re standing on an icy pond? Because ducks, like all other birds, have naturally cold feet and the temperatur­e difference isn’t enough to melt the ice. A duck’s foot temperatur­e is less than 35°F even though the rest of its body stays at a toasty 104°F. A duck’s counter-current blood circulatio­n system enables heat exchange among the blood vessels that supply the duck’s feet with enough blood to provide oxygen and just enough warmth to avoid frostbite.

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