Everything about Unionidae totally explained
Unionidae is a
family of freshwater
mussels distributed world-wide, but most diverse in North America with about 297 recognized taxa. Freshwater mussels occupy a wide range of habitats, but most often occupy lotic waters. The shell is equivalve and and has a thick
periostracum. The hinge mostly has two cardinals and two
posterior lamellar teeth.
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 bury themselves in the sediment.
Genera and species
Further Information
Get more info on 'Unionidae'.
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