any of about 18 species of marine fishes of the familes Ammodytidae and Hypotychidae (order Perciformes). Sand lances are slim, elongated, usually silver fishes especially abundant in northern seas. Although eel-like in shape and movement, they are not true eels. The species range from about 20 to 46 centimetres (8 to 18 inches) in length and are characterized by a forked tail, a long head, and a long dorsal fin. They live in schools, often under the sand below the surf. They are of little use to man but are a very important food for predacious fishes and sea birds.