Meet the frog that almost 'dies' each winter by freezing solid but comes back to life each spring

The Frog That Freezes Solid but Still Hops Back Alive (Image: Canva)

Picture observing a frog freeze like ice, then thaw and leap once more when spring comes. That is the remarkable survival strategy of the wood frog, a tiny animal that weathers the harsh Alaskan winter in a rather interesting method.

How do wood frogs survive Alaska's freezing cold?

Alaska's forests experience severe winters with temperatures close to minus 50 degrees Fahrenheit. In rare instances, it goes as low as minus 80 degrees. Most frogs escape such weather by concealing themselves underwater, where the temperature remains a little warmer. But wood frogs live on land, resting in leaf litter when the cold arrives. Food disappears, insects hide, and the frogs cannot stay active. Their only option is to sit out the winter.

What happens when wood frogs actually freeze?
When temperatures plunge, the water inside their bodies begins to freeze. Normally, this would rupture cells and damage blood vessels. Yet wood frogs use a different strategy. Their liver produces a sugar solution that works like antifreeze. This spreads through their cells, binds to water molecules, and stops them from freezing. Ice forms around their organs and under the skin, but the cells remain intact.

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Is this hibernation or something stranger?
Unlike animals in hibernation, frozen wood frogs have no heartbeat and no breath. They appear like solid ice, lifeless on the forest floor. When the spring sees temperatures rise, the leaf litter warms rapidly, thawing out the ice within their bodies. Their hearts begin anew, their muscles jerk, and before long they are hopping once again, off to ponds to breed. Incredible as it may seem, they have no injury from having spent weeks as frozen frogs.

The wood frogs' capability to freeze and recover tests our concepts of survival. It furthermore poses new questions concerning biology, adaptation, and even the endurance of life in extreme conditions.