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| The families of non-marine molluscs of Britain and Ireland (slugs, snails and mussels) |
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.
Representation in Britain and Ireland. Dreissena (1, “Zebra mussel”).
Illustrations. • Dreissena polymorpha (Reeve). DREISSENIDAE. Dreissena polymorpha (Pallas), "Zebra Mussel". From Reeve (1863), with scale added. • Dreissena polymorpha, with Anodonta spp. (Adams). UNIONIDAE. 1, Anodonta cygnea (Linn.), "Swan Mussel"; 2, Anodonta anatina (Linn.), "Duck Mussel". DREISSENIDAE. 3, Dreissena polymorpha (Pallas), "Zebra Mussel". From Adams (1896).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The families of non-marine molluscs of Britain and Ireland (slugs, snails and mussels). Version: 5th August 2019. delta-intkey.com’.
