The families of British non-marine molluscs (slugs, snails and mussels)


L. Watson and M. J. Dallwitz


Morphology. Mussels, enclosed by a hinged, bivalve shell.

Eyes absent (the animal with no head). Attaching to stones, etc., via a byssus.

The shell 25–40 mm in its maximum dimension; 25–40 mm wide (and about half as long across). The shell bent, with one margin quite sharply incurved and the other strongly curved outwardly. The shell opaque (and robust); yellowish, brownish or greyish, often with light-and-dark stripes.

General biology, ecology. Freshwater aquatic. Breathing via complex gills. In clean, well oxygenated, lowland rivers, canals and reservoirs, attaching to stones and other hard surfaces; sometimes in slightly brackish water.

Classification. Bivalvia.

British representation. Dreissena (1, “Zebra mussel”).

Illustrations. • Dreissena polymorpha (Reeve). • Dreissena polymorpha, with Anodonta spp. (Adams).

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The families of British non-marine molluscs (slugs, snails and mussels). Version: 4th January 2012.’.