Anomia ephippium Linnaeus, 1758Anomioidea : Anomiidae
To size: To 60mm. Shell Structure: Upper valve rather solid, lower valve thinner but robust. Equivalve: Inequivalve, upper (left) valve convex; lower (right valve) flat. Equilateral: Inequilateral, beaks close to the middle of the dorsal margin. Outline: Upper valve subcircular but irregular, lower valve similar with a large oval byssus foramen. Contour: Often deformed to fit shape of attachment area.
Sculpture: Upper valve surface scaly, may be worn smooth and lustrous but mostly overgrown with attached epifauna; lower valve scaly with comarginal lines and growth stops. Margin: Irregular but smooth. Ligament: In a half moon shaped pit beneath the beaks. Hinge: Obscure. Pallial Musculature: Upper valve with three scars, a large and small byssus muscle scar and a small adductor muscle scar; lower valve with a single adductor muscle scar. Periostracum: Obscure. Colour: White with pink, purple and beige zones showing when worn; lower valve white. Internal of both valves highly lustrous.
Distribution & Ecology
Low intertidal and sublittoral (rare beyond 20m) on the south and west coasts Britain, north to Shetland, and on all coasts of Ireland. Its occurrence on the east coast of Britain and in the North Sea is uncertain and requires confirmation from living specimens. Epifaunal, attached by the byssus to hard substrates mostly in sheltered conditions.
Continental Shelf (to 200m)
Juveniles & Similar Species
Key Features & Similar Species
Anatomy – Ctenidium with reflected filaments
Listed are literature citing Anomia ephippium Linnaeus, 1758. Reference containing the species Type Description is highlighted.
Linnaeus C 1758. Systema Naturae. Editio decima. 1. Regnum Animale Holmiae, Laurentii Salvii. 824pp.
Winckworth, R I922. Note on the British species of Anomia. Proceedings of the Malacological Society of London. 15: 32-34.
Yonge C M 1977. Form and Evolution in the Anomiacea (Mollusca: Bivalvia)-- Pododesmus, Anomia, Patro, Enigmonia (Anomiidae): Placunanomia, Placuna (Placunidae Fam. Nov.). Philosophical Transactions of the Royal Society of London Series B. 276: 453-523.
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