|The venerid species Austrovenus stutchburyi , the New Zealand cockle, is sold internationally as sea food.|
Heterodonta is a taxonomic subclass of saltwater clams, marine bivalve molluscs. This subclass includes the edible clams, the cockles and the Venus clams.
These bivalves are distinguished by having the two halves of the shell equally sized (i.e, they are equivalved) and having a few cardinal teeth separated from a number of long lateral teeth. Their shells lack a nacreous layer, and the gills are lamellibranch in form. Most species have a siphon.
In 2010, a new proposed classification system for the Bivalvia was published in by Bieler, Carter & Coan, revising the classification of the Bivalvia, including the subclass Heterodonta.The following tree is their info which has been updated with the latest information from the World Register of Marine Species:
Venerida is an order of mostly saltwater but also some freshwater bivalve molluscs. This order includes many familiar groups such as many clams that are valued for food and a number of freshwater bivalves.
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 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.
Myida is an order of saltwater clams, marine bivalve molluscs in the subclass Heterodonta. The order includes such bivalves as soft-shell clams, geoducks and shipworms.
Nuculidae is a family of small saltwater clams in the order Nuculida. Species in this family are commonly known as nut clams.
Anomalodesmata is an order 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.
The Vermetidae, the worm snails or worm shells, are a taxonomic family of small to medium-sized sea snails, marine gastropod molluscs in the clade Littorinimorpha. The shells of species in the family Vermetidae are extremely irregular, and do not resemble the average snail shell, hence the common name "worm shells" or "worm snails".
Obtortionidae is a family of sea snails, marine gastropod molluscs in the superfamily Cerithioidea, that is within the clade Cerithimorpha or in clade Sorbeoconcha.
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.
Poromyoidea is a superfamily of molluscs. It used to contain only the family Poromyidae, but now it also contains Cetoconchidae Ridewood, 1903, as CetoconchaDall, 1886 was removed from Poromyidae and given its own family, according to the World Register of Marine Species.
In May 2010, a new taxonomy of the Bivalvia was published in the journal Malacologia. 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.
Requieniidae is a family of rudists, in the order Hippuritida, which lived from 155.7 to 66.043 million years ago.
Megalodontoidea is a superfamily of fossil bivalves in the order Megalodontida.
Astartoidea is a superfamily of bivalves in the order Carditida. In the World Register of Marine Species (WoRMS), it is considered a junior synonym of Crassatelloidea, whereas in ITIS Crassatelloidea is a separate superfamily containing Crassatellidae.
Carditida is an order of marine bivalve clams.
Carditoidea is a superfamily of marine bivalve clams.
Crassatelloidea is a superfamily of bivalves in the order Carditida. In the World Register of Marine Species (WoRMS), Astartoidea is considered a junior synonym of Crassatelloidea, whereas in ITIS Astartoidea is a separate family containing Astartidae and Cardiniidae – Cardiniidae itself being classified instead in Carditoidea by WoRMS.
Archiheterodonta is an infraclass of bivalve molluscs. It consists of the Carditida and the extinct Actinodontida orders.