The Ostreidae, the true oysters, include most

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of molluscs commonly consumed as

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not al ...

Pearl oyster ''Pinctada'' is a genus of saltwater oysters, marine bivalve mollusks in the family Pteriidae. These pearl oysters have a strong inner shell layer composed of nacre, also known as "mother of pearl". Pearl oysters are not closely related to ei ...

s are not true oysters, and belong to the order

Pteriida The Pteriida are an order of large and medium-sized marine bivalve mollusks. It includes five families, among them the Pteriidae (pearl oysters and winged oysters). 2010 taxonomy In 2010, a new proposed classification system for the Bivalvia ...

. Like

scallop Scallop () is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families ...

s, true oysters have a central adductor muscle, which means the shell has a characteristic central scar marking its point of attachment. The shell tends to be irregular as a result of attaching to a substrate. Both

oviparous Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...

(egg-bearing) and larviparous (larvae-bearing) species are known within Ostreidae. Both types are

hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...

s. However, the larviparous species show a pattern of alternating sex within each individual, whereas the oviparous species are simultaneous

s, producing either female or male

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce t ...

s according to circumstances. Members of genus ''

Ostrea ''Ostrea'' is a genus of edible oysters, marine bivalve mollusks in the family Ostreidae, the oysters. Fossil records This genus is very ancient. It is known in the fossil records from the Permian to the Quaternary (age range: from 259 to 0. ...

'' generally live continually immersed and are quite flat, with roundish shells. They differ from most bivalves by having shells completely made up of

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

, but with internal muscle scars of

aragonitic Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including pre ...

composition. They fare best in somewhat

oligotroph An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments. Oligotrophs are characterized by slow growth, low rates o ...

ic water. They brood their fertilized eggs for various proportions of the period from

fertilization Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proce ...

to hatching. Members of genera ''

Saccostrea Rock oysters are true oysters of the genus ''Saccostrea'', belonging to the subfamily Saccostreinae of the family Ostreidae . MolluscaBase eds. (2022). MolluscaBase. Saccostrea Dollfus & Dautzenberg, 1920. Accessed through: World Register of ...

'', ''

Magallana ''Magallana'' is a genus of true oysters (family Ostreidae) containing some of the most important oysters used for food. Species in this genus have been moved from ''Crassostrea'' after it was found to be paraphyletic. Species Extant species ...

'', and ''

Crassostrea ''Crassostrea'' is a genus of true oysters (family Ostreidae) containing some of the most important oysters used for food. Some species in the genus have been moved to the genus '' Magallana''. Species Extant species Extant species include:< ...

'' generally live in the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

, broadcast sperm and eggs into the sea, and can thrive in

eutrophic Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytoplank ...

water. One of the most commonly cultivated oysters is the

Pacific oyster The Pacific oyster, Japanese oyster, or Miyagi oyster (''Magallana gigas''), is an oyster native to the Pacific coast of Asia. It has become an introduced species in North America, Australia, Europe, and New Zealand. Etymology The genus ''Mag ...

, which is ideally suited for cultivation in

seawater Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...

ponds.

Genera and species

* '' Alectryonella'' * ''

Agerostrea ''Agerostrea'' is an extinct genus of fossil oysters, marine bivalve molluscs in the family Ostreidae, the true oysters. The genus ''Agerostrea'' is present in the Maastrichtian, the upper stage of the Late Cretaceous The Cretaceous ( ) is a ...

'' Vialov 1936 * '' Anomiostrea'' * '' Booneostrea'' * ''

Sacco Sacco may refer to: * Sacco (clothing) (also Sakko), a type of jacket * Sacco (river), a river of central Italy * Sacco, Campania, a comune (municipality) in southern Italy * Sacco chair, by Piero Gatti, Cesare Paolini, Franco Teodoro * Ospedal ...

1897 (27 species) * ''

'' Salvi & Mariottini 2016 ** '' Magallana angulata'' (

Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biolog ...

, 1819)Bouchet, P.; Marshall, B. (2016). Magallana Salvi & Mariottini, 2016. In: MolluscaBase (2017). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=836032 on 2017-12-22 ** '' M. ariakensis'' (

Fujita Fujita (written: , or ) is a Japanese surname. Notable people with the surname include: *, Japanese handball player *, Japanese long-distance runner *Aya Fujita (born 1987), Japanese shogi player *Emi Fujita (born 1963), Japanese singer *, Japanes ...

, 1913) ** '' M. belcheri'' ( G. B. Sowerby II, 1871) ** '' M. bilineata'' ( Röding, 1798) ** '' M. dactylena'' ( Iredale, 1939) ** '' M. gigas'' ( Thunberg, 1793) ** '' M. hongkongensis'' ( Lam &

Morton Morton may refer to: People * Morton (surname) * Morton (given name) Fictional * Morton Koopa, Jr., a character and boss in ''Super Mario Bros. 3'' * A character in the ''Charlie and Lola'' franchise * A character in the 2008 film '' Horton H ...

, 2003) ** '' M. nippona'' ( Seki, 1934) ** '' M. revularis'' (

Gould Gould may refer to: People * Gould (name), a surname Places United States * Gould, Arkansas, a city * Gould, Colorado, an unincorporated community * Gould, Ohio, an unincorporated community * Gould, Oklahoma, a town * Gould, West Virginia, a ...

, 1861) ** '' M. sikamea'' ( Amemiya, 1928) * '' Cryptostrea''

Harry Harry may refer to: TV shows * ''Harry'' (American TV series), a 1987 American comedy series starring Alan Arkin * ''Harry'' (British TV series), a 1993 BBC drama that ran for two seasons * ''Harry'' (talk show), a 2016 American daytime talk show ...

1985 ( synonymous with ''

''Bouchet, P.; Gofas, S. (2017). Cryptostrea Harry, 1985. In: MolluscaBase (2017). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=415253 on 2017-12-21 ** '' C. permollis'' G.B.Sowerby II 1871 - sponge oyster * '' Dendostrea'' Swainson 1835 (12 species) ** '' D. frons'' L. 1758 - frond oyster **'' D. sandvicensis'' (G.B.Sowerby II )1871 - Hawaiian oyster * ''

Lopha ''Lopha'' is a genus of marine bivalve molluscs in the family Ostreidae. The genus ''Lopha'' is present from the Triassic period in the Lower Norian age (216.5 ± 2.0 – 203.6 ± 1.5 Mya) to the recent age. Description ''Lopha'' species ha ...

'' Röding 1798 ** '' L. cristagalli'' L. cockscomb oyster ** '' L. frons'' L. 1758 * '' Nanostrea'' * '' Nicaisolopha'' Vyalov 1936 * ''

'' L. 1758 (approx. 120 species) * '' Planostrea'' * '' Pretostrea'' * '' Pustulostrea'' * ''

'' (11 species) * '' Striostrea'' ** '' S. margariacea''

1819 - sand oyster ** '' S. denticulata'' Born 1778 ** '' S. prismatica''

Gray Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed o ...

1825 * '' Teskeyostrea''

1985 ** '' T. weberi''

Olsson Olsson is a common Swedish surname. It is a contraction of the surname Olofsson and it literally means "son of Olof" and seldom also "son of Ola". Notable people with the surname include: * Åke Olsson - Swedish football player * Åke Olsson (ch ...

1951 - threaded oyster, Weber oyster

References

{{Authority control Taxa named by Constantine Samuel Rafinesque Bivalve genera