(Linné, 1767)
Description (shell):
The shell is internal, covered over by the mantle, oval, frail, transparent, glossy, whitish, with little sculpture; the aperture is very wide and open, longer than the spire.
Size:
Body up to 70 mm, about twice as long as wide. Shell up to half body length.
Animal:
Translucent, white to pale yellow, with white dots, quadripartite. Cephalic shield longer than wide, indented posteriorly, may or may not be indented anteriorly. Parapodial lobes fleshy, rounded on outer sides, moulding to form of head and visceral hump. Mantle cavity widely open posteriorly, indented dorso-medially. The skin can secrete sulphuric acid as a defensive reaction (P. aperta-animal).
Habitat:
This common species occurs on and in offshore sand, through which it can burrow in search of its prey, consisting of small gastropods, bivalves and polychaete worms. It may itself be eaten by fish such as the haddock and some flatfish.
Distribution:
Distributed from Norway to the Mediterranean Sea, South Africa, Ceylon and the Philippines, to 500 m (Distr. P. aperta).