Mactridae,

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

the trough shells or duck clams, is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of saltwater clams, marine

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Venerida Venerida (formerly Veneroida) 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. Since the 2000s, ...

Description

These clams have two short siphons, each with a horny sheath. The shell is shaped like a rounded-cornered equilateral triangle and there is a slight gape at the posterior. Each valve bears two cardinal teeth with four lateral teeth on the right valve and two on the left. The foot is white and wedge-shaped. They mostly inhabit the

neritic zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminate ...

Ecology

Trough shells burrow in

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

or fine gravel and never in muddy substrates.

Subfamilies and genera

According to the

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive catalogue and list of names of marine organisms. Content The content of the registry is edited and maintained by scien ...

(2025), this family contains 56 genera and is split into the following subfamilies:

Subfamily Darininae

* '' Darcinia'' Clark, 1946 * '' Darina'' J. E. Gray, 1853

Subfamily Lutrariinae

* '' Eastonia'' J. E. Gray, 1853 * '' Heterocardia'' Deshayes, 1855 * ''

Lutraria ''Lutraria'' is a genus of medium-sized marine bivalve mollusks or clams, commonly known as otter shells. Characteristics Members of this genus have large, elongated oval shells with two equal sized valves. The anterior end is somewhat sharply ...

'' Lamarck, 1799 * '' Meropesta'' Iredale, 1929 * '' Standella'' J. E. Gray, 1853 * ''

Tresus ''Tresus'' is a genus of saltwater clams, marine bivalve mollusks in the family Mactridae. Many of them are known under the common name the horse clam or as species of gaper clam. They are similar to geoducks. Species Species within the genus ...

'' J. E. Gray, 1853 * ''

Zenatia ''Zenatia'' is a genus of medium-sized clams, marine bivalve molluscs in the family Mactridae. Distribution This genus is endemic to New Zealand. Species Species in the genus ''Zenatia'' include: * '' Zenatia acinaces'' ( Quoy and Gaimard J ...

'' J. E. Gray, 1853 * '' Zenatina'' Gill & Darragh, 1963

Subfamily Mactrinae

* '' Allomactra'' Tomlin, 1931 * '' Austromactra'' Iredale, 1930 * '' Barymactra'' Cossmann, 1909 * '' Coelomactra'' Dall, 1895 * ''

Crassula ''Crassula'' is a genus of succulent plants containing about 200 accepted species, including the popular jade plant (''Crassula ovata''). They are members of the stonecrop family (Crassulaceae) and are native to many parts of the globe, but culti ...

'' Marwick, 1948 * '' Cyclomactra'' Dall, 1895 * '' Diaphoromactra'' Iredale, 1930 * '' Harvella'' J. E. Gray, 1853 * '' Huberimactra'' Cosel & Gofas, 2018 * '' Leptospisula'' Dall, 1895 * ''

Mactra ''Mactra'' is a large genus of medium-sized marine bivalve mollusks or clams, commonly known as trough shells or duck clams. ''Mactra'' is the type genus within the family Mactridae.MolluscaBase eds. (2021). MolluscaBase. Mactra Linnaeus, 1767. ...

'' Linnaeus, 1767 * '' Mactrella'' J. E. Gray, 1853 * '' Mactrellona'' J. G. Marks, 1951 * '' Mactrinula'' J. E. Gray, 1853 * '' Mactromeris'' Conrad, 1868 * '' Mactrotoma'' Dall, 1894 * '' Maorimactra'' H. J. Finlay, 1928 * '' Mulinia'' J. E. Gray, 1837 * '' Oxyperas'' Mörch, 1853 * '' Pseudocardium'' Gabb, 1866 * '' Rangia'' Desmoulins, 1832 * '' Sarmatimactra'' Korobkov, 1954 * '' Scalpomactra'' H. J. Finlay, 1928 * '' Scissodesma'' Gray, 1837 * '' Simomactra'' Dall, 1894 * ''

Spisula ''Spisula'' is a genus of medium-sized to large Marine (ocean), marine bivalve mollusks or clams in the subfamily Mactrinae of the family (biology), family Mactridae, commonly known as surf clams or trough shells. MolluscaBase eds. (2022). Mollu ...

'' J. E. Gray, 1837 * '' Trinitasia'' Maury, 1928 * '' Tumbeziconcha'' Pilsbry & Olsson, 1935 * '' Mactrona'' Marwick, 1952 * '' Petromactra'' Saul, 1973

Subfamily Resaniinae

* '' Resania'' J. E. Gray, 1853

Subfamily Tanysiphoninae

* '' Tanysiphon'' W. H. Benson, 1858

''
Incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...
''

* '' Aktschagylia'' Starobogatov, 1970 * '' Aliomactra'' Stephenson, 1952 * '' Andrussella'' Korobkov, 1954 * '' Avimactra'' Andrusov, 1905 * '' Caspimactra'' A. A. Ali-Zade & Kabakova, 1969 * '' Chersonimactra'' Paramonova, 1978 * '' Cryptomactra'' Andrussow, 1902 * '' Cymbophora'' Gabb, 1869 * '' Eopapyrina'' Woodring, 1982 * '' Geltena'' Stephenson, 1946 * '' Ionesimactra'' Signorelli, 2023 * '' Kirghizella'' Andrusov, 1902 * '' Mactrodesma'' Conrad, 1869 * '' Mactrona'' Marwick, 1952 * '' Mulinoides'' Olsson, 1944 * '' Nelltia'' Stephenson, 1952 * '' Nymphactra'' Stilwell & Zinsmeister, 1992 * '' Ovamactra'' Woodring, 1982 * '' Petromactra'' Saul, 1973 * '' Planimactra'' Ionesi, 1986 * '' Podolimactra'' Ionesi, 1986 * '' Praerangia'' Cossmann, 1908 * '' Priscomactra'' Stephenson, 1952 * '' Pseudomactra'' Steklov, 1960 * '' Pteroluter'' Saul, 1973 * '' Stereomactra'' Stewart, 1930 * '' Stiphromactra'' Böhm, 1929 * '' Tenuimactra'' Garvie, 1996 * '' Willimactra'' Saul, 1973 * '' Zenatiopsis'' Tate, 1880

References

* Powell A. W. B., ''New Zealand Mollusca'', William Collins Publishers Ltd, Auckland, New Zealand 1979 Bivalve families Taxa named by Jean-Baptiste Lamarck Extant Cretaceous first appearances {{Bivalve-stub