Prawn

Prawns are decapod crustaceans, belonging to the sub-order Dendrobranchiata. 3 The term "prawn" is also used in various contexts for other animals, especially caridean shrimp. 4 They are found worldwide and include commercially significant species, such as the whiteleg shrimp Litopenaeus vannamei, Atlantic white shrimp Penaeus setiferus, Indian prawn Fenneropenaeus indicus, giant river prawn Macrobrachium rosenbergii and tiger prawn Penaeus monodon.

Prawns are similar in appearance to other small, swimming decapods, such as shrimp Caridea and boxer shrimp Stenopodidea , but can be distinguished by the gill structure which is branching in prawns hence the name, dendro tree branchia gill , but is lamellar in shrimp. One exception is the family Luciferidae, which lack gills as adults. 5 Prawns usually have claws on three pairs of their legs, while shrimp only have claws on two. 6 The sister taxon to Dendrobranchiata is Pleocyemata, which contains all the true shrimp, crabs, lobsters, etc. Unlike almost all other decapods, prawns do not brood their eggs on the pleopods, but release the eggs into the water after fertilisation.

Living prawns are divided among seven families, five in the superfamily Penaeoidea, and two in the Sergestoidea, 2 although molecular evidence disagrees with some aspects of the current classifications. 8 Collectively, these include 540 extant species, and nearly 100 exclusively fossil species. 1 A further two families are known only from fossils.