Frogs, Turtles Freeze Solid in Winter, Come Back to Life in Spring

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NBC Today Show
Jane Pauley/Robert Bazell
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Video News Report
NBCUniversal Media, LLC.
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In 1988, researchers discover that turtles and frogs freeze solid in winter, producing a natural antifreeze -- glucose sugar -- that protects their organs until they thaw in warmer temperatures.



"Frogs, Turtles Freeze Solid in Winter, Come Back to Life in Spring." Robert Bazell, correspondent. NBC Today Show. NBCUniversal Media. 29 Nov. 1988. NBC Learn. Web. 17 January 2015.


Bazell, R. (Reporter), & Pauley, J. (Anchor). (1988, November 29). Frogs, Turtles Freeze Solid in Winter, Come Back to Life in Spring. [Television series episode]. NBC Today Show. Retrieved from


"Frogs, Turtles Freeze Solid in Winter, Come Back to Life in Spring" NBC Today Show, New York, NY: NBC Universal, 11/29/1988. Accessed Sat Jan 17 2015 from NBC Learn:


Frogs, Turtles Freeze Solid in Winter, Come Back to Life in Spring

JANE PAULEY, anchor:

On Today’s Discovery science correspondent Robert Bazell tells us about some creatures that can freeze but not freeze to death. Just freeze and then come back to life. Good Morning.

ROBERT BAZELL, reporting:

Good Morning, who says we don’t cover the world. Until very recently, scientists had thought that higher animals like us were not capable of surviving a hard freeze, as frozen as the vegetables in your freezer. But recently they discovered that some frogs and turtles can freeze, and this has opened up a fascinating new line of research. Janet and Ken Story are out looking for places where frogs and turtles spend the winter.

JANET STORY (Scientist): Oh look, a wood frog.

BAZELL: What is unusual about these animals is that they don’t simply hibernate.

KEN STORY (Scientist): In this nitch, in this ecological nitch a lot of animals just dig down a little bit, bury themselves in the wet dirt and spend the winter frozen solid.

JANET STORY: See if we got any live hatchlings here.

KEN STORY: There should be.

BAZELL: Until just a few years ago scientists did not realize that any vertebrates, animals with backbones, were capable of surviving after freezing. But they now know that some frogs and turtles do it every year. The Story’s study this phenomenon in this laboratory at Carlton University in Ottawa.

KEN STORY: To take an animal, a vertebrate to higher form of life with a brain, a heart, a liver, freeze it solid and then watch it come back to life, it’s tremendously interesting to us, what are the mechanisms, how does it do it, how is it controlled?

BAZELL: As part of their experiments, the scientists freeze frogs and turtles. They attach some measuring instruments to them and simply put them in the deep freeze.

JANET STORY: This is a natural temperature that the wood frog would see out of doors.

BAZELL: Hours, days or weeks later, they take them out and defrost them. When the animal is frozen, all of the blood is concentrated around the heart which doesn’t beat. In fact neither the brain nor any organ in the body functions.

KEN STORY: They’re now hard and crunchy and make a sound when you drop them.

JANET STORY: Their eyes are sort of glazed over, the limbs are very hard, you can barely move them. He’s very icy, he feels like a little frog popsicle actually. These animals have been in, been frozen for maybe twelve or fifteen hours now, and they should be near their maximal ice content.

BAZELL: Once out of the freezer the frog defrosts and in a few minutes comes back to life, returns to normal.

KEN STORY: The limbs are the first to thaw with ice leaving the skin, the skin’s now soft and subtle, whereas before it was solid as a rock. The animal isn’t injured at all, you can feel his heart has begun to beat again and he’s begun to get active.

BAZELL: The Story’s have found that the frogs and turtles manage to survive by manufacturing an anti-freeze, glucose sugar. They produce large amounts of it,\ and that protects the cells in the body. The researchers are trying to find out exactly how this system works. They measure the amounts of energy going in and out of the frog as it freezes and unfreezes. They also analyze the chemistry of the glucose anti-freeze process. The hope is that the findings could someday prove useful in medicine.

KEN STORY: In the bigger picture we’re of course trying to discover the mechanisms in order to apply them to even higher forms of life. Does the frog and the turtle in the way they freeze, in the protectants they put out, in the way they can survive ice tell us something about how we can take a human organ, freeze it solid, keep it for some period of time, thaw it and have it survive as well.

BAZELL: But even if such applications are never found, the sight of a frozen animal coming back to life will remain fascinating. This is truly interesting to me, that no vertebrate had ever been known to do this before, they suddenly discover that these things could come back to life after being essentially dead for months or even years.

PAULEY: Science is catching up with Hollywood, I think Hollywood has known for years.

BAZELL: Yea Hollywood knew it for, well Hollywood’s done a lot of things for years, but I think that this is a lot better, and also the possibility of freezing transplanted organs, that’s an interesting idea.