(Olivi, 1792)
Description (shell):
Shell thin and brittle, umbones close to midline, prominent and bulbous. Anterior half of shell semi-elliptical, posterior drawn out as a tapered spout, truncate at its end. Both valves strongly convex. Sculpture of numerous fine lines and ridges, somewhat coarser posteriorly and towards margins. Ligament supported in each valve by an elliptical chondrophore, prominent in right valve but recessed below hinge line in left. Right valve with one elongate posterior lateral tooth, fitting beneath the left hinge line. Adductor scars and pallial line distinct, pallial sinus shallow.
Size:
Up to 20 mm long.
Colour:
White; periostracum brown, coarse, often corrugate, with adhering sediment. Inner surfaces white.
Animal:
The siphons are relatively short and the hinder part of the shell is drawn out to partially cover them; their orifices are protected by long tentacles whose ends are divided into several finger-like points. The Cuspidarians are the only truly carnivorous bivalves. The gill is a muscular septum and the pumping and sucking action of this draws in food consisting mainly of dead crustacea (C. cuspidata-animal).
Habitat:
In muddy sand and gravel, offshore.
Distribution:
Distributed from Norway to the Mediterranean and West Africa (Distr. C. cuspidata).