Shrimp, any of the approximately 2,000 species of the suborder Natantia (order Decapoda of the class Crustacea). Close relatives include crabs, crayfish, and lobsters. Shrimp are characterized by a semitransparent body flattened from side to side and a flexible abdomen terminating in a fanlike tail. The appendages are modified for swimming, and the antennae are long and whiplike. Shrimp occur in all oceans—in shallow and deep water—and in freshwater lakes and streams. Many species are commercially important as food. Shrimp range in length from a few millimetres to more than 20 cm (about 8 inches); average size is about 4 to 8 cm (1.5 to 3 inches). Larger individuals are often called prawns.