Conchostraca (clam shrimps; class Branchiopoda, order Diplostraca) Suborder of branchiopods called ‘clam shrimps’ because the body is almost or completely enclosed in a bivalved carapace, which is folded, rather than being hinged dorsally, and closed by a transverse adductor muscle. The compound eyes are sessile, and the second antennae are well developed, biramous, and setose, and augment the trunk limbs in locomotion. There are 10–32 trunk segments, each with a pair of appendages. There are 180 species.

Diplostraca(clam shrimps, water fleas; subphylum Crustacea, class Branchiopoda) Order of branchiopods in which the body is laterally compressed and at least partially enclosed in a bivalved carapace. The order comprises two suborders: Conchostraca (clam shrimps) and Cladocera (water fleas). There are 605 species.