The very well developed gastric armature of the littoral mysid, Gastrosaccus simulans (Van Benedeo) shows that filter feeding has lost much of its importance in the animal and that it feeds mainly on large food masses. The hepatopancreas is very elaborately branched and very complex in structure. Paired glandular ridges are present in all the tubules of the hepatopanoreas. The food consists of a wide variety of animal and vegetable matter. The animal is cannibalistic, feeding on disabled companions.