Conchostraca is an order in the Superorder Diplostraca in the Class Branchiopoda, but newer research indicates that it is perhaps not a monophyletic group after all. A paraphyletic origin within Diplostraca would mean that a new classification is needed. Commonly called the clam shrimp or claw shrimp, they have a two-parted shell like that of a bivalve mollusc. Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ... Subclasses and Orders Subclass Sarsostraca Order Anostraca (fairy shrimp) Subclass Phyllopoda Order Notostraca (tadpole shrimp) Superorder Diplostraca Order Cladocera (water fleas) Order Conchostraca (clam shrimps) Suborder Laevicaudata Suborder Spinicaudata Suborder Cyclestherida Branchiopoda is a group of primitive and primarily fresh water crustaceans, mostly resembling shrimp. ... In phylogenetics, a group is monophyletic (Greek: of one stem) if all organisms in that group are known to have developed from a common ancestral form, and all descendants of that form are included in the group. ... Paraphyletic - Wikipedia /**/ @import /skins-1. ... Orders Subclass Protobranchia Solemyoida Nuculoida Subclass Pteriomorphia - oysters Arcoida Mytiloida Pterioida Subclass Paleoheterodonta - mussels Trigoinoida Unionoida Subclass Heterodonta - clams, zebra mussels Veneroida Myoida Subclass Anomalosdesmata Pholadomyoida Animals of the Class Bivalvia are known as bivalves because they typically have two-part shells, with both parts being more or less symmetrical. ...