Linné, 1758
Description (shell):
Shell smooth, with no growth rings or ridges; markedly tapered to posterior end and with a pronounced curve. Anterior aperture circular; posterior end obliquely truncate, aperture oval with a notch on convex side, occluded by a calcified septum with a central tube (pipe), having a pyriform orifice (D. entalis-drawing).
Size:
Up to 40 mm long, maximum width of 5 mm at anterior end.
Colour:
Shell glossy white.
Animal:
The animal is white and of similar shape as its shell, with a rudimentary eyeless head, which is covered by the mantle as in the bivalves. The foot, which projects from the large end of the shell, has lobes which are scalloped irregularly. The radula within the buccal mass is broad and oval, with only 5 teeth in a row. The sexes are separate, but there is neither special respiratory organ, heart, nor circulatory system. The edges of the mantle are united, so that it forms a open tube, and the entire surface of this appears to absorb oxygen.
Habitat:
Offshore in sand.
Distribution:
All coasts, but uncommon in south; not present around Channel Isles (Distr. D. entalis).