Lophogastrida is an order of malacostracan crustaceans in the superorder Peracarida, comprising shrimp-like animals that mostly inhabit the relatively deep pelagic waters of the oceans throughout the world. Most lophogastridan species are 1–8 centimetres (0.4–3.1 in) long, but Gnathophausia ingens can be up to 35 cm (14 in), probably the largest pelagic crustacean in the world. Some 56 extant species in total are currently known. They are classified into three families and nine genera.