small flat-bodied semi-terrestrial crustaceans: whale lice; sand-hoppers; skeleton shrimp

Amphipoda (amphipods) is an order of animals that includes over 7000 described species of small, shrimp-like crustaceans.

A numerous group of fourteen -- footed Crustacea, inhabiting both fresh and salt water. The body is usually compressed laterally, and the anterior pairs or legs are directed downward and forward, but the posterior legs are usually turned upward and backward. The beach flea is an example. See Tetradecapoda and Arthrostraca.