Amphipods

Amphipods, an order of small sessile-eyed crustaceans, with laterally compressed bodies, and long abdomen with three pairs of swimming appendages in front, and behind these three backward turned springing feet. The thoracic or anterior legs bear the gills. The order includes a great number of common forms—e.g. the familiar Sand-hopper, q.v. (Talitrus saltator); another very frequent genus, Orchestia, sometimes much more terrestrial than the former; the abundant Gammarus of running water; the wood-boring Limnoria and Chelura; the blind Niphargus of underground fresh water; the quaint Spectre or Skeleton Shrimp, q.v. (Caprella); and many more. See CRUSTACEA.