Wood louse, also called sow bug, is a small invertebrate (animal without a backbone) that lives on land. There are many different species (kinds) of wood lice. They belong to a group of animals known as isopods, about half of which live in the ocean. Like its marine relatives, a wood louse has a flat, oval body that is divided into a number of segments. Special muscles enable the animal to roll up into a ball when disturbed.
Most wood lice live in dark, damp, humid places, such as under stones and in bark. They come out only at night to feed. A few species live in the desert. They burrow deep into the sand to avoid daytime heat.
