The Ostreidae, the true oysters, include most

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 no ...

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 ...

s are not true oysters, and belong to the order

Pteriida The Pteriida are an order (biology), order of large and medium-sized Marine (ocean), marine bivalve mollusc, mollusks. It includes five families, among them the Pteriidae (pearl oysters and winged oysters). 2010 taxonomy In 2010, a new propos ...

. Like

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

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 reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

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

hermaphrodite A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

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 ( ) is a Ploidy#Haploid and monoploid, haploid cell that fuses with another haploid cell during fertilization in organisms that Sexual reproduction, reproduce sexually. Gametes are an organism's reproductive cells, also referred to as s ...

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 Although molecular studies suggest that ''Ostrea'' first appeared around the Eocene and originated no earlier than the Cre ...

'' 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 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 American and British English spelling differences#-ise, -ize (-isation, -ization), spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give ...

to hatching. Members of genera '' Saccostrea'', ''

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 a ...

'', and '' Crassostrea'' generally live in the

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

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

eutrophic Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...

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 ''Magal ...

, which is ideally suited for cultivation in

seawater Seawater, or sea 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 approximat ...

ponds.

Subfamilies and genera

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 ...

accepts 16 genera split into 4 subfamilies.

Subfamily Crassostreinae

*†'' Angustostrea'' Vialov, 1936 *'' Crassostrea''

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 * Ospe ...

, 1897 *†'' Cubitostrea'' Sacco, 1897 *†'' Ferganea'' Vialov, 1936 *†'' Gyrostrea'' Mirmakolov, 1966 *''

'' Salvi & Mariottini, 2016 *'' Talonostrea'' X.-X. Li & Z.-Y. Qi, 1994

Subfamily Ostreinae

*†'' Actinostreon'' Bayle, 1878 *'' Alectryonella'' Sacco, 1897 *'' Anomiostrea'' T. Habe & Kosuge, 1966 *'' Booneostrea'' Harry, 1985 *'' Dendostrea'' Swainson, 1835 *'' Lopha'' Röding, 1798 *'' Nanostrea'' Harry, 1985 *''

'' L., 1758 *'' Planostrea'' Harry, 1985 *'' Pustulostrea'' Harry, 1985 *'' Teskeyostrea'' Harry, 1985 *†'' Umbrostrea'' Hautmann, 2001

Subfamily Saccostreinae

*'' Saccostrea'' Dollfus & Dautzenberg, 1920

Subfamily Striostreinae

*'' Striostrea'' Vialov, 1936

''
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 ...
''

*†'' Kulunostrea'' J.-M. Wei, 1984 *'' Nicaisolopha'' Vyalov, 1936 *†'' Pseudoperna'' Logan, 1899 *†'' Sokolowia'' Böhm, 1933

References

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