The frog that freezes and comes back to life

The North American wood frog has an extreme way of getting through winter: it freezes almost entirely and waits for spring.

When the cold arrives, much of the water in its body turns to ice. Its heart stops, it stops breathing and its brain activity shuts down: from the outside, it looks dead. The key is that its liver floods the cells with glucose, which acts as a natural antifreeze and keeps the ice from destroying them from within.

When the warmth returns, the frog thaws little by little, its heart starts up again and the animal hops away as if nothing had happened. A whole winter on pause, and then it just carries on living.

Source: National Geographic