| | 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 animals with no developed head). Without a byssus.
The shell (55–)70–130(–200) mm in its maximum dimension; (55–)70–130(–200) mm wide (about half as long across the shell from the hinge, somewhat more in A. anatina). The shell oblong, with the margin opposite the hinge more or less straight or only slightly incurved, or not bent, the margin opposite the hinge outwardly curved. The shell opaque (and robust); brown, bright or dark greenish or greenish brown, glossy. The shells brown, bright or dark greenish or greenish brown, glossy.
General biology, ecology. Freshwater aquatic. Breathing via complex gills. Burrowing in the substrate, in still or slow-moving waters - rivers, canals, lakes and reservoirs.
Classification. Bivalvia.
Representation in Britain and Ireland. Anodonta (2, “Swan mussel and Duck mussel”), Pseudanodonta (1, “Compressed River mussel”), Unio (2, including “Painter’s mussel and Swollen River mussel”).
Illustrations. • Bivalvia: Margaritifera, Musculium, Pisidium, Sphaerium, Unio (Adams). SPHAERIIDAE. 1, Sphaerium corneum (Linn.), "Horny Orb Mussel"; 2, Sphaerium rivicola (Lamarck), "Nut Orb Mussel, River Orb Mussel". 3, Musculium transversum (Say), "Oblong Orb Mussel"; 4, Musculium lacustre (Müller), "Lake Orb Mussel, Capped Orb Mussel". 5, Pisidium amnicum (Müller), "River Pea Shell, Giant Pea Shell"; 6, Pisidium pulchellum Jenyns; 7, Pisidium obtusale (Lamarck); 8, Pisidium nitidum Jenyns; 9, Pisidium milium Held, "Rosy Pea Shell". UNIONIDAE. 10, Unio tumidus Philipsson, "Swollen River Mussel:; 11, Unio pictorum (Linn.), "Painter's Mussel". MARGARITIFERIDAE. 12, Margaritifera margaritifera (Linn.), "Freshwater Pearl Mussel, Scottish Pearl Mussel". From Adams (1896). • Bivalvia: Anodonta and Dreissena (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’.
