American oyster (Crassostrea virginica)
|Researched by||Susie Ballerstedt||Refereed by||Admin|
|Other common names||-||Synonyms||-|
Recorded distribution in Britain and Ireland
Introduced to the south east and south west of England and north Wales.
Distributed along the coast of North America from St Lawrence to the Gulf of Mexico and Panama.
This species can be found on the lower shore and shallow sublittoral. It is a prolific species in its native home and can be found on any hard surface, often becoming long and distorted when overcrowded. It is tolerant to very low salinity.
- Shell can grow up to 18 cm in length.
- Left valve is convex and sculptured.
- Right valve is flat.
- Shell margin is smooth.
- Outer shell surface is deep purple or reddish brown.
Additional informationSimilar to Magallana gigas (Thunberg) but lacks the bold ribs and crenulate shell margin typical of Magallana gigas. Both Crepidula fornicata and Urosalpinx cinera were introduced with Crassostrea virginica (Yonge & Thompson, 1976). Crepidula fornicata out-competes the American oyster for space, whereas Urosalpinx cinerea is a common predator of Crassostrea virginica. However, if the shell of the oyster is over 0.4 cm thick at the point of attack then Urosalpinx cinerea will be unsuccessful (Wilbur, 1988).
Crassostrea virginica reproduces externally with both eggs and sperm being discharged through the exhalent siphon. Over 100 million eggs may be liberated from a single female. Spawning of one individual also induces spawning in the surrounding population, therefore maximizing gamete interaction. Interestingly, spawning is temperature dependent; populations in cool temperate waters only spawn at 17°C, while populations in slightly warmer waters spawn at 20°C and sub-tropical populations spawn at 25°C. When transplanted to a different habitat individuals will not spawn, which together with competition and predation pressure from Crepidula fornicata and Urosalpinx cinerea respectivily, are likely explanations for the unsuccessful establishment of Crassostrea virginica.
- none -
Beaumont, A.R., Newman, P.B., Mills, D.K., Waldock, M.J., Miller, D. & Waite, M.E., 1989. Sandy-substrate microcosm studies on tributyl tin (TBT) toxicity to marine organisms. Scientia Marina, 53, 737-743.
Bowden, J. & Heppell, D., 1966. Revised List of British Mollusca 1. Introduction; Nuculacea-Ostreacea. Journal of Conchology, 26, 99-124.
Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.
Seaward, D.R., 1990. Distribution of marine molluscs of north west Europe. Peterborough: Nature Conservancy Council.
Tebble, N., 1976. British Bivalve Seashells. A Handbook for Identification, 2nd ed. Edinburgh: British Museum (Natural History), Her Majesty's Stationary Office.
Wilbur, K.M., 1988. The Mollusca. Volume II: Form and Function. London: Academic Press Inc. Ltd.,
Yonge, C.M. & Thompson, T.E., 1976. Living Marine Molluscs London: Collins.
Yonge, C.M., 1960. Oysters. London: Collins.
Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) records for Great Britain and Ireland. Occurrence dataset: https://doi.org/10.15468/aurwcz accessed via GBIF.org on 2018-09-25.
NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.
OBIS (Ocean Biodiversity Information System), 2023. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2023-11-28
This review can be cited as:
Last Updated: 08/07/2008