Short clip from a 2005 Nova Science Now, on North American Wood Frogs. A touch of ice immediately sets off signals inside the frog, says Professor John Costanza, that pull water away from the center of its body. So the frog's internal organs are now wrapped in a puddle of water that then turns to solid ice. There is no breathing, no kidney function, the heart stops. The frog's blood sugar is distributed through the circulatory system and works like an antifreeze. It's harder for water to freeze, so cells stay just damp enough for the animal to hold itself together, until the springtime, when the days grow a little longer and the ground gets a little warmer and then, well, a kind of miracle happens.

After weeks or months of no heartbeat, none, suddenly there's a pulse. And that first heartbeat leads to another and then another and then, within a day, and—in the case of this little frog, it took about 10 hours—the animal literally comes back to life.