Unionidae

Unionidae is a family of freshwater mussels, the largest in the order Unionoida, the bivalve mollusks sometimes known as river mussels, naiads, or simply as unionids.

The range of distribution for this family is world-wide. It is at its most diverse in North America, with about 297 recognized taxa, but China and Southeast Asia also support very diverse faunas.

Freshwater mussels occupy a wide range of habitats, but most often occupy lotic waters.

Life habits

Unionidae burrow into the substrate, with their posterior margins exposed. They pump water through the incurrent aperture, obtaining oxygen and food.

Unionidae are distinguished by a unique and complex life cycle. Most Unionids are of separate sex (although some species, such as Elliptio complanata, are known to be hermaphroditic). The sperm is ejected from the mantle cavity through the male’s excurrent aperture and taken into the female's mantle cavity through the incurrent aperture. Fertilized eggs move from the gonads to the gills (marsupia) where they further ripen and metamorph into glochidia, the first larval stage. Mature glochidia are released by the female and then attach to the gills, fins or skin of a host fish. A cyst is quickly formed around the glochidia, and they stay on the fish for several weeks or months before they fall off as juvenile mussels which then bury themselves in the sediment.

Genera

Genera within the family Unionidae include: Genus Actinonaias
Genus Alasmidonta
Genus Amblema
Genus Anodonta
Genus Cucumerunio Iredale, 1934
Cucumerunio websteri delli, McMichael & Hiscock, 1958
Cucumerunio websteri websteri, Simpson, 1902
Genus Elliptio
Genus Epioblasma
Genus Fusconaia
Genus Hamiota
Genus Hyridella Swainson, 1840
New Zealand freshwater mussel, Hyridella menziesi, Gray, 1843
Genus Lampsilis
Genus Lasmigona
Genus Leptodea
Genus Ligumia
Genus Obliquaria
Genus Plethobasus
Genus Pleurobema
Genus Pseudanodonta
Depressed river mussel, Pseudanodonta complanata
Genus Ptychobranchus
Genus Pyganodon
Genus Quadrula
Genus Quincuncina
Genus Sinanodonta
Sinanodonta woodiana
Genus Strophitus
Genus Truncilla
Genus Unio
Genus Utterbackia
Genus Villosa

Translation

The word "Unionidae" occurs as such in the following languages: English, French, Portuguese.

Translation(s) in other languages: Estonian: Jõekarplased, Latvian: Dižgliemeņu dzimta, Dutch: Najaden (Unionidae), Polish: Skójkowate, Swedish: Målarmusslor.