Happening unseenAmphibians
How wood frogs freeze solid in winter and come back in spring
When: December to February
Wood frogs do not dig deep or find shelter. They settle into the leaf litter and freeze, heart and all, and stay that way until the ground warms. Through the deep-winter stretch, nothing about them is beating.
Why this time of year
They are frozen for as long as the ground is, which here is the deep-winter stretch. The thaw is not gradual for them: they come back over hours, and the first warm rain of March is when the woods suddenly have frogs in it again.
How to notice it
- There is nothing to see, and that is the card. Stand on frozen woodland leaf litter and know what is in it.
- The liver floods the body with glucose as the skin starts to freeze, and that syrup is what keeps the cells from being destroyed.
- The heart slows, then stops. It is not slowed down, it is stopped, and it restarts on thawing.
- Come back to the same wood on the first warm rainy night of March and listen. These are the frogs that make the racket.
Try this with kids: There are frogs frozen in the ground under your feet right now. What do you think wakes them up?
glucose is a sugar; the frog floods itself with it, and the syrup keeps its cells from being wrecked by ice
Sources
- nationalgeographic.comQuoting researcher Kenneth Storey: the frog's liver pumps out incredible amounts of glucose, a syrupy liquid acting as antifreeze for vital organs; ice pushes blood to the frog's heart before eventually that too is rock solid; in spring the sun shines, mud forms, they warm up and they thaw. Wood frogs in Alaska freeze down to minus 5 degrees Fahrenheit, others in North Carolina cool to 8.6 degrees
In the guide for December, January, February