; subclass Actinopterygii, order Clupeiformes)
A large family of mainly marine fish which have compressed, streamlined bodies with a single, soft-rayed, dorsal fin half-way down the back, and a forked tail fin. Nearly all clupeids have protruding scales, giving the ventral side a rough or serrated appearance. The family includes many commercially important species, e.g. Clupea harengula (herring), Sardina pilchardus (pilchard), and Brevoortia tyrannus (Atlantic menhaden). Some species, e.g. Dorosoma cepedianum (American gizzard shad), are found only in freshwater systems. Like many other clupeids, they move in large schools, feeding on plankton. They are found world-wide, in temperate and tropical waters.
Subjects: Zoology and Animal Sciences.