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Imagine That! -- "Frozen Frogs"

Imagine That!
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Imagine That! -- "Frozen Frogs"

Credit: NSF/Finger Lakes Productions International

Audio Transcript:

(SOUND: strong winds howling)

Did you feel frozen solid this past winter? Couldn't wait for your vacation to thaw out? Turns out you're not the only one!

Imagine That!

(SOUND: frogs)

The tiny North American wood frog, found in forests from northern America to the Artic Circle, actually accomplishes this amazing feat. At the first sign of ice in late fall or winter, the frog immediately starts to freeze, with ice spreading to all parts of its body. Its internal organs, such as the heart and lungs, stop functioning when they become frozen and encased in ice. The frog essentially freezes as solid as a rock, but can recover fully after thawing.

(SOUND: water dripping)

It does it by circulating glucose through its body. The glucose acts as a type of antifreeze, lowering the amount of ice that forms in its tissues and preventing damage to its cells. When warmer weather arrives, the frogs are hoppin' around again after a ten-hour thaw. Even weirder, the frogs actually thaw from the inside out--organs first, then limbs!

(SOUND: hospital monitors beeping)

John Costanzo, a biologist at Miami University in Ohio, studies this phenomenon, and hopes it may lead to new technology to preserve human organs destined for transplantation. With more than eighty-five thousand patients on transplant waiting lists, this is news worth croaking about. I'm Eric Phillips.

"Imagine That!" covers projects funded by the U.S. government's National Science Foundation. Federally sponsored research -- brought to you, by you! Learn more at

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