The roughly 40 known species of lophogastrids were formerly combined with another group of Peracarida, the Mysida, as the Mysidacea. Most are between 1 and 8 cm long, but Gnathophausia ingens may reach 35 cm. All lophogastrids are pelagic (i.e., open water) swimmers and the group is distributed throughout the world's oceans. Lophogastrids feed mainly on zooplankton. (Brusca and Brusca 2003) An excellent online source on the Lophogastrida is Gary Anderson's Peracarida Taxa and Literature website.