In spring and summer, a country pond is abuzz with the loud croaking of frogs. But when winter comes and the pond freezes over, the sound of frogs disappears. It may seem that all the frogs have died.
Actually, when cold weather comes, most frogs bury themselves in the soft mud at the bottom of the pond. The surface of the pond freezes over, but all the water below it does not turn to ice. Therefore, the frog’s winter home remains unfrozen.
Frogs hardly move around at all while they’re wintering at the bottom of the pond, so they need very little oxygen for energy. What little they need, they get directly from the water, through openings in their skin.
Then when spring comes and the pond thaws, the frogs leave their winter home and swim to the surface to begin another summer of croaking.