What is crustacean

Crabs, prawns, shrimps, and lobsters belong to a group of invertebrates called crustaceans. They have hard shells and often walk around on jointed legs. A crustacean is group of animals that includes crabs, lobsters, crayfish, and shrimp. Crustaceans form a large, diverse arthropod taxon which includes such animals as crabs, lobsters, crayfish, shrimp, krill, prawns, woodlice, barnacles.