Nucula nucleus (Linnaeus, 1758)Nuculoidea : Nuculidae
Inequilateral, the beaks lie approximately 25-30% of dorsal margin length from posterior.
Rounded triangular: height of shell approximately 85% of length; antero-dorsal margin long, rounded, concave and sloping; postero-dorsal margin slightly concave to almost straight, steeply sloping with angled junction at posterior margin; anterior and posterior margins narrowly rounded; ventral margin more deeply rounded; escutcheon heart-shaped, slightly projecting, generally with defined edges in older individuals; lunule long, lanceolate with poorly defined edges.
Sculpture: Primary sculpture of numerous very fine, closely-spaced, radial riblets, most visible near the outer margin. Some comarginal lines and growth stops. Older individuals have a decussate surface near the outer margin. Margin: Inner margin crenulate in correspondence to riblets. Ligament: Internal, opisthodetic, with the ligament seated in a well-developed, rounded resilifer. A thin, barely visible, external ligament lies anterior to the beaks. Hinge: Taxodont: Broad and continuous hinge plate with a well-developed triangular shaped resilifer. Teeth long and pointed, usually 11-14 posterior and 16-25 anterior. The teeth extend across the top of the resilifer. Pallial Musculature: Pallial line continuous with no pallial sinus. Adductor muscle scars oval, more or less equal in size and indistinct. Periostracum: Smooth, matt surface, grey-green to olive coloured, very occasionally with orange or purple-grey coloured rays. Shells often coated with deposits of manganese, particularly around the posterior end. Colour: White. Inside of shell nacreous.
Distribution & Ecology
Occurs all around the coasts of Britain and Ireland.
North-east Atlantic, Mediterranean, west Africa. Lives in sand, gravel, shell gravel and pebble, less often in silt or mud. Lives from the near sub-tidal to the outer continental shelf (180-200m depth).
Continental Shelf (to 200m)
Juveniles & Similar Species
Key Features & Similar Species
Listed are literature citing Nucula nucleus (Linnaeus, 1758). Reference containing the species Type Description is highlighted.
Allen J A 1954. A comparative study of the British species of Nucula and Nuculana. Journal of the Marine Biological Association of the United Kingdom. 33: 457-472.
Gofas S & Salas C 1996. Small Nuculidae (Bivalvia) with functional primary hinge in the adults. Journal of Conchology. 35: 427-435.
Linnaeus C 1758. Systema Naturae. Editio decima. 1. Regnum Animale Holmiae, Laurentii Salvii. 824pp.
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