The common name for swimming crustaceans, most marine but some inhabiting fresh water, belonging to the suborder Dendrobranchiata (order Decapoda). Typically, a prawn has a robust body, a large head with antennae, stalked eyes, and mandibles, a carapace covering the thorax and extending forwards as a rostrum, five pairs of walking legs borne on the thorax, and an abdomen of similar length to the combined head and thorax. Larger species tend to be called prawns and smaller ones shrimps, but there is no significant difference. There are about 540 species found worldwide.