mantis shrimp, marine crustacean characterized by a pair of enlarged appendages, called maxillipeds, that form powerful claws for seizing prey. The last two segments of each of these legs are strong and sharp, and the end segment is folded back over the next segment to make a scissorslike cut. Mantis shrimps have stalked eyes and flattened abdomens with appendages bearing gills. They prefer warm shallow seas. A number of species are quite large, reaching 1 ft (30 cm) or more in size. Mantis shrimps are an important sea food outside the Western Hemisphere. They are classified separately from either true shrimps or praying mantises, whose forelimbs the maxillipeds superficially resemble. Mantis shrimps are grouped in the phylum Arthropoda, subphylum Crustacea, class Malacostraca.