Prawns are shrimp–like crustaceans, belonging to the sub-order Dendrobranchiata .

Prawns are distinguished from the superficially similar shrimp by the gill structure which is branching in prawns (hence the name, dendro=“tree”; branchia=“gill”), but is lamellar in shrimp. The sister taxon to Dendrobranchiata is Pleocyemata, which contains all the true shrimp, crabs, lobsters, etc.

The largest prawn is commonly called the giant tiger prawn, which can weigh up to 650 g (23 ounces).