Russ Kinne/Photo Researchers. Crustaceans are animals that usually have a hard covering, or exoskeleton, and two pairs of antennas, or feelers. People around the world eat many types of crustaceanfor example, crabs, lobsters, shrimps (or prawns), and crayfish. Barnacles, water fleas, and pill bugs are also crustaceans. All crustaceans are arthropods.