The order Ostreida includes the true oysters. One superfamily (Ostreoidea) and two extant families are recognised within it. The two families are Ostreidae, the true oysters, and Gryphaeidae, the foam oysters.
The Arcida is an extant order of bivalve molluscs. This order dates back to the lower Ordovician period. They are distinguished from related groups, such as the mussels, by having a straight hinge to the shells, and the adductor muscles being of equal size. The duplivincular ligament, taxodont dentition, and a shell microstructure consisting of the outer crossed lamellar and inner complex crossed lamellar layers are defining characters of this order.
The Pteriida are an order of large and medium-sized marine bivalve mollusks. It includes five families, among them the Pteriidae.
The Pteriomorphia comprise a subclass of saltwater clams, marine bivalve molluscs. It contains several major orders, including the Arcida, Ostreida, Pectinida, Limida, Mytilida, and Pteriida. It also contains some extinct and probably basal families, such as the Evyanidae, Colpomyidae, Bakevelliidae, Cassianellidae, and Lithiotidae.
Palaeoheterodonta is a subclass of bivalve molluscs. It contains the extant orders Unionida and Trigoniida. They are distinguished by having the two halves of the shell be of equal size and shape, but by having the hinge teeth be in a single row, rather than separated into two groups, as they are in the clams and cockles.
Heteroconchia is a taxonomic infraclass of saltwater clams, marine bivalve molluscs, belonging to the subclass Autobranchia.
Trigonioidea is superfamily of medium-sized saltwater clams, marine bivalve molluscs. Within the fossil record the occurrence of this superfamily is widespread, ranging from the Devonian Period to Recent.
Mytilidae are a family of small to large marine and brackish-water bivalve molluscs in the order Mytilida. One of the genera, Limnoperna, even inhabits freshwater environments. Mytilidae, which contains some 52 genera, is the only extant family within the order Mytilida.
Unionida is a monophyletic order of freshwater mussels, aquatic bivalve molluscs. The order includes most of the larger freshwater mussels, including the freshwater pearl mussels. The most common families are the Unionidae and the Margaritiferidae. All have in common a larval stage that is temporarily parasitic on fish, nacreous shells, high in organic matter, that may crack upon drying out, and siphons too short to permit the animal to live deeply buried in sediment.
Anomalodesmata is an superorder of saltwater clams, marine bivalve molluscs. This grouping was formerly recognised as a taxonomic subclass. It is called a superorder in the current World Register of Marine Species, despite having no orders, to parallel it with sister taxon Imparidentia, which does have orders.
Sportellidae is a family of marine bivalve molluscs of the superfamily Cyamioidea.
Protobranchia is a subclass of bivalve molluscs. It contains the extant orders Nuculanida, Nuculida, and Solemyida.
Pectinida is a taxonomic order of large and medium-sized saltwater clams, marine bivalve molluscs, commonly known as scallops and their allies. It is believed that they began evolutionarily in the late Middle Ordovician epoch; many species, of course, are still extant.
Fordilloidea is an extinct superfamily of early bivalves containing two described families, Fordillidae and Camyidae and the only superfamily in the order Fordillida. The superfamily is known from fossils of early to middle Cambrian age found in North America, Greenland, Europe, the Middle East, Asia, and Australia. Fordillidae currently contains two genera, Fordilla and Pojetaia each with up to three described species while Camyidae only contains a single genus Camya with one described species, Camya asy. Due to the size and age of the fossil specimens, Fordillidae species are included as part of the Turkish Small shelly fauna.
Trigoniida is an order of medium-sized saltwater clams, marine bivalve molluscs. Within the fossil record the occurrence of this order is widespread, ranging from the Devonian Period to Recent.
In May 2010, a new taxonomy of the Bivalvia was published in the journal Malacologia. The 2010 taxonomy is known as the Taxonomy of the Bivalvia . The 2010 taxonomy was published as Nomenclator of Bivalve Families with a Classification of Bivalve Families. This was a revised system for classifying bivalve mollusks such as clams, oysters, scallops, mussels and so on. In compiling this new taxonomy, the authors used a variety of phylogenetic information including molecular analysis, anatomical analysis, shell morphology and shell microstructure, as well as bio-geographic, paleobiogeographical and stratigraphic information.
Mytilus unguiculatus, common name the Korean mussel or the hard-shelled mussel, is a species of mussel, a marine bivalve mollusc in the family Mytilidae. This species is heavily exploited as a food item via mariculture in Korea and in China. It is also a typical macrofouling organism.
Mytiloidea are a superfamily of small to large saltwater mussels, marine bivalve molluscs in the order Mytilida.
Lucinida is a taxonomic order of saltwater clams, marine bivalve molluscs.
Carditida is an order of marine bivalve clams.
