Prawns are decapod crustaceans of the suborder Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian. They differ from other, similar crustaceans, such as Caridea (shrimp) and Stenopodidea (boxer shrimp) by the branching form of the gills and by the fact that they do not brood their eggs, but release them directly into the water. They may reach a length of over 330 millimetres (13 in) and a mass of 450 grams (1.0 lb), and are widely fished and farmed for human consumption.