BIOTIC Species Information for Ostrea edulis
Researched byAngus Jackson Data supplied byMarLIN
Refereed byThis information is not refereed.
Scientific nameOstrea edulis Common nameNative oyster
MCS CodeW1758 Recent SynonymsNone

PhylumMollusca Subphylum
Superclass ClassPelecypoda
Subclass OrderOstreoida
SuborderOstreina FamilyOstreidae
GenusOstrea Speciesedulis

Additional InformationAlso commonly known as the flat oyster and European oyster.
Taxonomy References Howson & Picton, 1997, Hayward & Ryland, 1995b, Campbell, 1994, Christensen, 1980, Anonymous, 1999(b), Tebble, 1966, Yonge, 1960, Korringa, 1952,
General Biology
Growth formBivalved
Feeding methodActive suspension feeder
Mobility/MovementPermanent attachment
Environmental positionEpifaunal
Typical food typesSuspended organic particles. HabitAttached
BioturbatorNot relevant FlexibilityNone (< 10 degrees)
FragilityRobust SizeSmall-medium(3-10cm)
HeightInsufficient information Growth RateInsufficient information
Adult dispersal potentialNone DependencyIndependent
General Biology Additional InformationThere is some evidence that reduced growth, weight and poor conditions are a consequence of high population densities (300 per square yard). Size and shape can be extremely variable. Because the oyster cements itself to the substratum, growth of neighbouring individuals may result in competition or space and distort the usual shell shape. Feeding is carried out by pumping water through a filter in the gill chamber removing suspended organic particles. The native oyster starts life as male, becoming mature at around 3 years of age. After spawning the oyster becomes a functional female. Larvae are seldom produced by oysters under 50 mm. Growth is quite rapid for the first year and a half. It then remains constant at around 20 grams per year before slowing down after five years. In the British Isles, the main growing season is from April to October. The oyster faces serious competition from the introduced species Crepidula fornicata, the slipper limpet. Brought over from the United States this species can occur in very high densities competing for space and food. The slipper limpet deposits pseudo faeces which forms 'mussel mud' changing the substratum and hindering settlement. Native oysters are preyed on by a variety of species including starfish and Ocenebra erinacea, the sting winkle or rough tingle. Buccinum undatum, the common whelk also feeds on oysters but not as exclusively as the sting winkle. Urosalpinx cinerea, the American oyster drill was accidentally introduced to the British Isles with American oysters. This species lives on oyster beds and feeds almost entirely on oyster spat.
Biology References Lilley, 2000, Dare, 1982, Sheldon, 1968, Richardson et al., 1993, Askew, 1972, Hutchinson & Hawkins, 1992, Yonge, 1960, Korringa, 1952,
Distribution and Habitat
Distribution in Britain & IrelandWidely distributed around the British Isles but less so on the east and north-east coasts of Britain and Ireland. The main stocks are now in the west coast of Scotland, the south-east and Thames estuary, the Solent, the River Fal, and Lough Foyle.
Global distributionFound naturally from the Norwegian Sea south through the North Sea down to the Iberian Peninsula and the Atlantic coast of Morocco. Found in the Mediterranean Sea and extends into the Black Sea.
Biogeographic rangeNot researched Depth range0-80m
MigratoryNon-migratory / Resident   
Distribution Additional InformationThe native oyster has also been introduced and is cultivated in North America, Australia and Japan. Cultivated populations may be encouraged through the use of an artificial substratum (limed tiles) used preferentially for larval settlement. Oysters are found on a wide variety of substrata but typically where the seabed is hard. Can form into dense 'beds' of oyster shells.

Substratum preferencesLarge to very large boulders
Small boulders
Gravel / shingle
Artificial (e.g. metal/wood/concrete)
Muddy gravel
Muddy sand
Physiographic preferencesOpen coast
Ria / Voe
Biological zoneLower Eulittoral
Sublittoral Fringe
Upper Infralittoral
Lower Infralittoral
Upper Circalittoral
Lower Circalittoral
Wave exposureExposed
Moderately Exposed
Very Sheltered
Extremely Sheltered
Tidal stream strength/Water flowInsufficient information
SalinityFull (30-40 psu)
Variable (18-40 psu)
Habitat Preferences Additional Information
Distribution References Hayward & Ryland, 1995b, Campbell, 1994, Anonymous, 1999(b), Tebble, 1966, Lilley, 2000, Yonge, 1960, Korringa, 1952, Moore, 2002,
Reproduction/Life History
Reproductive typeProtandrous hermaphrodite
Developmental mechanismPlanktotrophic
Reproductive SeasonJune to September Reproductive LocationAs adult
Reproductive frequencyAnnual protracted Regeneration potential No
Life span6-10 years Age at reproductive maturity3-5 years
Generation timeInsufficient information FecundityUp to 2,000,000 in large females
Egg/propagule sizeca 150 µm diameter Fertilization typeInternal
Larval/Juvenile dispersal potential>10km Larval settlement periodInsufficient information
Duration of larval stage11-30 days   
Reproduction Preferences Additional InformationA life span of 5-10 years is probably typical (majority of individuals in populations are 2-6 years old). However, they may reach in excess of 15 years old. Oysters are protandrous alternating hermaphrodites. This means that they start off as males producing sperm then switch to egg producing females, back to males and so on. Gamete maturation begins in March or April and is in part temperature dependent. Gametogenesis may be continuous in warmer conditions e.g. California. On the west coast of Ireland there is at least one spawning in each sexual phase during the summer. There may be some periodicity in spawning with peaks during full moon periods. Fecundity may be as high as 2,000,000 in large individuals. The eggs are around 150 microns in diameter. Eggs produced during the female stage are held in the gills and mantle cavity. The eggs are fertilized by sperm drawn in by the inhalant water flow used for feeding and respiration. The fertilized eggs are retained for 7-10 days for the early development until the veliger stage is reached. This is sometime called larviparous or incubatory development.
Reproduction References Lilley, 2000, Dare, 1982, Orton, 1936, Wilson & Simons, 1985, Yonge, 1960, Korringa, 1952,
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