Purperslakken en de variabiliteit van het operculum bij Nucella lapillus in een kolonie te Audresselles, Frankrijk

In April 2007 the first two authors investigated the rocky outcrops on the beach of Audresselles, France, for the presence of marine molluscs. Special attention was paid to Nucella lapillus (Linnaeus, 1758), also known as the Atlantic dogwhelk. A study of the collected material revealed that some of the specimens possessed a strongly reduced operculum. Some animals were even completely devoid of an operculum. The aim of this article is to provide some general information concerning Nucella lapillus in general and the variability of the operculum in particular.