The common wood frog (Rana sylvatica) has an unusual strategy for coping with the cold. While most terrestrial frogs and toads burrow deep underground to escape freezing temperatures when they hibernate, the wood frog spends its winters at the surface. The frog tucks itself into shallow depressions, covered only by a blanket of leaf litter. There it undergoes a transformation that would kill most other vertebrates: It freezes solid.

Believe it or not, this overwintering deep freeze is how it survives the cold… and the colder the better. Watch Invisible Nature: Return of the Wood Frog, a bioGraphic film by Flora Lichtman, to learn more about the wood frog’s biological superpower, an incredible chemical secret that allows it to thaw from the inside out when spring temperatures return.

Next: How Do Trees Survive Winter? and Where Do Birds Go In Winter?

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