The Dreissenidae are a family of small freshwater mussels, aquatic

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of marine and freshwater Mollusca, molluscs that have laterally compressed bodies enclosed by a shell consisting of two hing ...

molluscs. They attach themselves to stones or to any other hard surface using a

byssus A byssus () is a bundle of filaments secreted by many species of bivalve mollusc that function to attach the mollusc to a solid surface. Species from several families of clams have a byssus, including pen shells ( Pinnidae), true mussels (Mytili ...

. The shells of these bivalves are shaped somewhat like those of true

mussel Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which ...

s, and they also attach themselves to a hard substrate using a

, however this group is not at all closely related to true mussels, being more closely related to the venus clams ( Veneridae).

Genera

Genera within the family Dreissenidae include: * ''

Congeria ''Congeria'' is a genus of bivalves belonging to the family Dreissenidae The Dreissenidae are a family of small freshwater mussels, aquatic bivalve molluscs. They attach themselves to stones or to any other hard surface using a byssus. The she ...

'', a unique genus of cave-dwelling bivalves * ''

Dreissena ''Dreissena'' is a genus of small freshwater mussels in the family Dreissenidae in the class Bivalvia. They are found attached to firm substrates by threads from underneath the shells and are the only freshwater bivalves to attach to hard substr ...

'', the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal ...

of the family * ''

Mytilopsis ''Mytilopsis'' is a genus of small fresh- and brackishwater mussels in the family Dreissenidae The Dreissenidae are a family of small freshwater mussels, aquatic bivalve molluscs. They attach themselves to stones or to any other hard surfa ...

'' * '' Rheodreissena'', a newly described South American genus

Shell morphology

The shells of species of mussels in this family range from 20–40 mm in their maximum dimension, and about half as wide across. The shell outline is bent, with one margin usually somewhat incurved, and the other strongly curved outwardly. The shell is opaque and robust; in coloration it is yellowish, brownish or greyish, often with light-and-dark stripes.

Biology and ecology

These mussels breathe via complex gills. They live in clean, well oxygenated, lowland rivers, canals and reservoirs, attaching to stones and other hard surfaces; they will also tolerate slightly

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estua ...

water.

Geographical range of distribution

In Britain there is only one species from this family, '' Dreissena polymorpha'', the zebra mussel, which is a troublesome

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...

. In the USA, both ''D. polymorpha'' and '' D. bugensis'' are problematic introduced species.

References

External links

{{Taxonbar, from=Q1257898 Dreissenidae, Bivalve families