Native Oyster - Ostrea Edulis

Phylum - Mollusca

Class - Pelecypoda

Order - Ostreoida

Family - Ostreidae

Genus - Ostrea

Species - Edulis

Size - Body Length : Up to 110mm

Also commonly known as the flat oyster and European oyster.


Ostrea edulis is associated with highly productive estuarine and shallow coastal water habitats on firm bottoms of mud, rocks, muddy sand, muddy gravel with shells and hard silt. In exploited areas, suitable habitat is/has been created in the form of 'cultch' - broken shells and other hard substrata.


Ostrea edulis is a bivalve mollusc that has an oval or pear-shaped shell with a rough, scaly surface. The two halves (valves) of the shell are different shapes. The left valve is concave and fixed to the substratum, the right being flat and sitting inside the left. The shell is off-white, yellowish or cream in colour with light brown or bluish concentric bands on the right valve. Ostrea edulis grows up to 110 mm long, rarely larger. The inner surfaces are pearly, white or bluish-grey, often with darker blue areas.

Key Features

  • Shell inequivalve, lower (left) valve convex and upper valve flat sitting within the lower.
  • Periostracum thin, dark brown.
  • Outer surface rough and scaly with concentric sculpture and fine radiating ridges.
  • Yellowish or cream in colour with light brown or bluish concentric bands on the right valve.
  • Hinge line without teeth in the adult.
  • Adductor muscle scar white, or slightly discoloured.

Minimum sizes

Do not take Oysters more than 110mm shell length or less than 70mm.

Should not fit through a Oyster ring of 110mm diameter.

Recorded Distibution

Widely 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.

Ostrea edulis recorded (•) distribution in Britain and Ireland

Habitat Preferences

Physiological Preference - Open Coast / Sealoch / Ria or Voe / Estuary
Biological Zone Preference - Lower Eulittoral / Sublittoral Fringe / Upper Infralittoral / Lower Infralittoral Upper Circalittoral / Lower Circalittoral
Substratum / habitat preferences - Large to very large boulders Small boulders Cobbles Pebbles Gravel / shingle Artificial (metal, wood, concrete) Muddy gravel Muddy sand Mud
Tidal strength preferences - N/A
Wave exposure preferences - Exposed / Moderately Exposed / Sheltered / Very Sheltered / Extremely Sheltered
Salinity preferences -Full (30-40 psu) Variable (18-40 psu)
Depth in Metres - 0-80m

Need to measure Oysters?

Why not look at our Oyster measuring guage page.

Fishing Gauges by Alexander Pollock
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