“Freezes into a solid frog-shaped ice cube all winter, then thaws back to life.”

Every winter, the wood frog does something that should be impossible: it dies, more or less, and gets better in spring. As the cold sets in, two-thirds of the water in its body turns to ice. Its heart stops. Its breathing stops. Its brain goes quiet. For weeks or months it is, by most measures, a frozen frog-shaped lump in the leaf litter. The trick is a flood of glucose and urea it pumps into its cells like antifreeze, keeping the ice outside the cells where it can't shred them. When spring warms the ground, the frog thaws from the inside out, the heart stutters back to life, and it hops off to find a pond and start singing for a mate as if nothing happened. It's one of the few animals that ranges above the Arctic Circle, surviving the cold by simply surrendering to it.

Scientific name

Lithobates sylvaticus

Size

Smaller than a teabag (4–7 cm).

Habitat

Forests and tundra across North America, into the Arctic.

Diet

Insects, spiders, slugs, and other small invertebrates.

Conservation

LC · Least Concern

Picnic threat level

Picnic threat: none in summer. In winter, it's a decorative ice cube.

Brian Gratwicke, CC BY 2.0, via Wikimedia Commons · Learn more →