; class Malacostraca, superorder Hoplocarida)
Order of crustaceans, 5–36 cm long, many of which are brightly coloured, with striped or mottled patterns. The body is flattened dorsoventrally and there is a shield-like carapace. The entire dorsal surface is armed with ridges and spines, and the abdomen is broad and segmented. The head has stalked, compound eyes with a median nauplius eye; large, triramous, first antennae; and smaller third antennae. The thoracic appendages are uniramous and subchelate, with the second pair modified for raptorial prey capture. As the common name implies, the large second thoracic appendages are equipped with a movable process armed with spines and barbs. Prey is caught or speared by a rapid extension of this process. Many species inhabit bottom burrows or crevices in coral or rock, and defend their burrows using the telson as a shield. They may leave their burrows to stalk prey (e.g. crabs) and swim using their pleopods, steering by means of their large antennal scales and uropods. Apart from Isopoda, mantis shrimps are the only malacostracans that have abdominal gills. Many species exhibit parental care of their eggs. They comprise the only order of their superorder, with approximately 300 species. Most are tropical but some live in temperate waters.
Subjects: Zoology and Animal Sciences.