''Ostrea edulis'', commonly known as the European flat oyster, is a species of

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 ...

native to

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

. In Britain and Ireland, regional names include Colchester native oyster, mud oyster, or edible oyster. In France, ''Ostrea edulis'' are known as ''huîtres plates'' (flat oysters) except for those that come from the Belon River estuary in

Brittany Brittany (; french: link=no, Bretagne ; br, Breizh, or ; Gallo: ''Bertaèyn'' ) is a peninsula, historical country and cultural area in the west of modern France, covering the western part of what was known as Armorica during the period ...

, France, which are known as Belons. The fossil record of this species dates back to the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

(age range: 15.97 million years ago to present day). Fossils have been found in Belgium, Italy, the Netherlands, Egypt, Greece, Spain, the United Kingdom, Austria, France and Germany.

Description

When mature, ''O. edulis'' adults range from across. Shells are oval or pear shaped, white, yellowish or cream in colour, with a rough surface showing pale brown or bluish concentric bands on the right valve. The two valves are quite different in shape and size, as the left one is concave and fixed to the substratum, while the right one is almost flat and fits inside the left. The inner surface is smooth, whitish or bluish-grey. Ostreidae - Ostrea edulis

Biology

''Ostrea edulis'' are gregarious molluscs that start their lives as males. They mature sexually after eight–ten months and may change sex depending on the water temperature. Usually the lifespan can reach about six years, with a maximum of 15 years. Adult oysters feed by filtration. Ostrea edulis 001

Distribution

The species naturally ranges along the western and southern coasts of

from

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of ...

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to A ...

and including most of the

British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isl ...

and the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...

coast. Naturally viable populations have appeared in eastern

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

from

Maine Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and nor ...

Rhode Island Rhode Island (, like ''road'') is a U.S. state, state in the New England region of the Northeastern United States. It is the List of U.S. states by area, smallest U.S. state by area and the List of states and territories of the United States ...

subsequent to artificial introduction in the 1940s and 1950s.

Habitat

''Ostrea edulis'' can be found in estuarine and shallow coastal water with hard substrata of mud and rocks.

Human use

''Ostrea edulis'' has been harvested throughout Europe as an important food source since prehistory. During Roman occupation of Britain ''O. edulis'' oysters were exported in large quantities back to Italy. However, due to their robust nature and ease of cultivation 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 ...

s, ''

Crassostrea gigas 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 ''Ma ...

'', account for more than 75 percent of Europe's oyster production. European flat oysters are famously grown in Brittany, France. The true Belon oyster is cultivated in the Belon River, France, and has the AOC protected name. In the 1950s, Dutch scientists artificially introduced Belon oyster seed into the waters around

in hopes to establish a viable stock. The initial project was abandoned but ten years later natural colonies of flat oysters were found in the wild. Many North American suppliers use the name 'Belon' to species that are found in the wild throughout the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

''Ostrea edulis'' is now also being

mariculture Mariculture or marine farming is a specialized branch of aquaculture (which includes freshwater aquaculture) involving the cultivation of marine organisms for food and other animal products, in enclosed sections of the open ocean ( offshore m ...

d in the states of

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

, and

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

in the United States. The species once dominated European oyster production but disease, pollution, and overfishing sharply reduced the harvest. Currently, there are efforts across Germany, the UK, France, Scotland, and Wales to restore oyster reefs and maintain the habitat. U.S. oyster growers farm ''O. edulis'' in small quantities on both coasts. They are prized for their unique tannic seawater flavour, sometimes described as dry and metallic, and are more expensive than other American oysters. The flavour is considered excellent for eating raw on the half shell. The adductor muscle of the European flat in combination with the shape of the shell results in a somewhat weaker seal compared with other oyster species. It is common practice to use rubber bands to prevent oysters from spilling their liquor and dehydrating in storage before consumption.

References

External links

UK Biodiversity Action Plan
{{Taxonbar, from=Q729678 Ostrea Commercial molluscs Molluscs described in 1758 Taxa named by Carl Linnaeus