The Class Crustacea is an extremely diverse group of arthropods found primarily in aquatic or marine habitats, including such forms as shrimp, crabs, lobsters, and barnacles. Only one group, the isopods, have invaded terrestrial habitats.
Sowbugs (Order Isopoda). (Fig. 7.1) The Sowbug is a widespread, extremely successful crustacean. Sowbugs have a gray-black segmented carapace, have seven
pairs of legs, and are commonly seen around habitations or where the ground is watered. Some are capable of rolling up into a ball and are known as pillbugs.