Earthworms in Winter

During winter most worms stay in their burrows, prisoners below soil frozen hard as rock and topped by ice and snow. They are coiled into a slime-coated ball and go into a sleep-like state called estivation, which is similar to hibernation for bears. (The mucous, or slime, keeps the worms from drying out.) Worms will survive in frozen or dry soils by estivation until conditions improve.

Not all kinds of earthworms make that downward journey to survive winter. Some kinds of earthworms lay their eggs in cocoons safe in the soil to hatch when conditions are right. Then they settle under leaf litter on top of the soil, where winter's cold makes them freeze and die.