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

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L. Watson and M. J. Dallwitz

Unionidae

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.

British representation. 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). • Bivalvia: Anodonta and Dreissena (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. http://delta-intkey.com’.

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