Turtles, like other cold-blooded animals, cannot remain active in cold weather. Species that live in regions with harsh winters must hibernate. Most freshwater turtles hibernate by burrowing into the warm, muddy bottom of a pond, stream, or other body of water. Land turtles bury themselves in soil or under rotting vegetation. Some species of turtles survive hot, dry periods by going into a state of limited activity called estivation.
Estivation somewhat resembles hibernation.
Mud and musk turtles make up a family of 22 fresh-water species. They live in the Western Hemisphere, particularly in Central America. Mud and musk turtles of the United States include the common mud turtle, common musk turtle, razor-backed musk turtle, and yellow mud turtle. But these turtles have large heads and strong jaws, and they may bite. When disturbed, these turtles give off a foul-smelling substance called musk from glands on the bridge in front of their hind legs.