These animals are somewhat flattened, and several times longer than wide. The top and sides of animals in this group are covered by a row of tough plates. Underneath they have 7 pairs of legs. On the head is a pair of antennae. Some species can curl up into a ball for protection, this is where they get the name "pillbug."
This is a group of over 3,800 species that are found all over the world. Most species of Isopods are marine, but this group evolved to live on land.
Pillbugs live just about anywhere there is moisture and dead plants to eat, but they are most common in forests and other humid habitats. A few live along the seashore, close to their marine relatives. They need humid conditions to survive.
Like all arthropods, sowbugs have to shed their exoskeleton to grow. Once these little animals leave their mother's pouch (see below), they don't change shape or structure much, they just get bigger.
These animals don't move around too much. They avoid light and dryness. They aren't particularly social, but some are apparently attracted to the smell of their own kind.
These animals have poor vision, and probably communicate chemically.
Pillbugs graze on algae, fungus, moss, bark, and all kinds of decaying plant and animal material.
Sowbugs and pillbugs roll up to protect themselves, they also have glands that make defensive chemicals. Their nocturnal habit probably helps them avoid some predators too.
These animals are part of the community of species that break down dead plants and animals.
Some species of pillbugs and sowbugs that live in people's gardens have been accidentally transported all around the world, and are found on all continents.