Unlike true crabs, hermit crabs have soft, vulnerable abdomens. For protection from predators, many hermit crabs seek out abandoned shells, usually snail shells. When a hermit crab finds one of the proper size, it pulls itself inside, leaving several legs and its head outside the shell. (A hermit crab has five pairs of legs, but not all of them are fully developed.) A hermit crab carries the shell wherever it goes. When it outgrows its shell, it switches to a larger one. Most adult hermit crabs are from 1/2 inch (13 mm) to 4 3/4 inches (121 mm) long. Living on the seashore, in tidepools, and on the sea bottom in deeper water, hermit crabs scavenge their food.