tegastidae is a family of copepods, which are characterised by having laterally compressed bodies (resembling that of an amphipod), a claw-like mandible in the nauplius stage, and by a modified male genital complex. 85 species have been described in 6 genera. two species of "smacigastes" are found at hydrothermal vents, while the remaining species are found in shallow water, associated with algae, bryozoans and cnidarians, such as corals.