Helcion pellucidum (Linnaeus, 1758)
Author & date of last revision: Steve Wilkinson on 1 February 2010
Patina pellucida; Helcion laevis; Patina laevis (Pennant, 1777);
Conical shell up to 20mm in length (var. pellucidum tends to be smaller). Shell is brown or olive in colour and can either be tranlucent (var. pellucidum) or opaque (var. laevis). The surface of the shell is smooth with very fine radiating ridges. Conical shaped Var. laevis tends to have a thinker shell and more pronounced conical shape.
Key identification features
Ecology and behaviour
Typically found on Laminaria but may also occur on fucoids. There are two varieties: var. pellucidum which occurs on the fronds and stipe of the Laminaria and var. laevis which occupies the holdfast. Breeds mainly in winter and spring. Fertilisation is external and the larvae initially settle on fucoids, migrating to Laminaria when they are about 4mm in length.
Distribution and status
Found on all Atlantic coasts from Portugal to the north of Norway.