The oyster mussel (''Epioblasma capsaeformis'') is a rare

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

freshwater mussel Freshwater bivalves are one kind of freshwater mollusc, along with freshwater snails. They are bivalves that live in fresh water as opposed to salt water, which is the main habitat type for bivalves. The majority of species of bivalve molluscs ...

in the family

Unionidae The Unionidae are a family of freshwater mussels, the largest in the order Unionida, the bivalve molluscs sometimes known as river mussels, or simply as unionids. The range of distribution for this family is world-wide. It is at its most diverse ...

. This aquatic

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

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

is native to the

Cumberland Cumberland ( ) is a historic county in the far North West England. It covers part of the Lake District as well as the north Pennines and Solway Firth coast. Cumberland had an administrative function from the 12th century until 1974. From 19 ...

and

Tennessee River The Tennessee River is the largest tributary of the Ohio River. It is approximately long and is located in the southeastern United States in the Tennessee Valley. The river was once popularly known as the Cherokee River, among other names, ...

systems of

Kentucky Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north; West Virginia and Virginia to ...

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

Alabama (We dare defend our rights) , anthem = "Alabama (state song), Alabama" , image_map = Alabama in United States.svg , seat = Montgomery, Alabama, Montgomery , LargestCity = Huntsville, Alabama, Huntsville , LargestCounty = Baldwin County, Al ...

, and

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

in the United States. It has been

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

from the states of

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...

''Epioblasma capsaeformis''.
The Nature Conservancy. and

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

.USFWS
Oyster mussel in North Carolina.
/ref> It is a federally listed

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

of the United States. This mussel was once widely distributedUSFWS
''Epioblasma capsaeformis'' Five-year Review.
July 2011 and common. It has declined 80% from its historical abundance. It is now extirpated from the Cumberland River system and the main artery of the Tennessee River. It remains in the

Nolichucky River The Nolichucky River is a river that flows through Western North Carolina and East Tennessee, in the southeastern United States. Traversing the Pisgah National Forest and the Cherokee National Forest in the Blue Ridge Mountains, the river's wate ...

of Tennessee and the

Clinch River The Clinch River is a river that flows southwest for more than through the Great Appalachian Valley in the U.S. states of Virginia and Tennessee, gathering various tributaries, including the Powell River, before joining the Tennessee River in Ki ...

in Tennessee and Virginia. Specimens once classified as this species that remain in the Duck River in Tennessee have now been classified as a separate species, ''

Epioblasma ahlstedti ''Epioblasma ahlstedti'', commonly called the Duck River dartersnapper, is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels. It is native to Alabama and Tennessee in the southeastern United S ...

''.Jones, J.W., and R.J. Neves. 2010. "Descriptions of a new species and a new subspecies of freshwater mussels, ''Epioblasma ahlstedti'' and ''Epioblasma florentina aureola'' (Bivalvia: Unionidae), in the Tennessee River drainage, USA." The Nautilus 124(2):77-92.Jones, J. W., et al. (2006)
A holistic approach to taxonomic evaluation of two closely related endangered freshwater mussel species, the oyster mussel ''Epioblasma capsaeformis'' and tan riffleshell ''Epioblasma florentina walkeri'' (Bivalvia: Unionidae).
''J. Mollus. Stud.'' 72 (3): 267-283. This mussel is elliptical or obovate in shape and reaches a maximum length of 70 mm. The posterior end of males protrudes slightly, while females are more rounded. The

periostracum The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods and ...

is sunshiny, yellowish green, with green rays over the entire shell. The

nacre Nacre ( , ), also known as mother of pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer; it is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is f ...

color is bluish-white to creamy. Like other freshwater mussels, this species is reproduces by releasing its larvae, termed

glochidia The glochidium (plural glochidia) is a microscopic larval stage of some freshwater mussels, aquatic bivalve mollusks in the families Unionidae and Margaritiferidae, the river mussels and European freshwater pearl mussels. These larvae are ...

, which lodge in the gills of fish to develop into juvenile mussels.Vincie, M. E
Development of a suitable diet for endangered juvenile oyster mussels ''Epioblasma capsaeformis'' (Bivalvia: Unionidae) reared in a captive environment.
Master's Thesis. Virginia Tech. Host fish species for this mussel include

wounded darter The wounded darter (''Etheostoma vulneratum'') is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is endemic to the e ...

(''Etheostoma vulneratum''), redline darter (''E. rufilineatum''), bluebreast darter (''Etheostoma camarum''), dusky darter (''Percina sciera''),

banded sculpin The banded sculpin (''Cottus carolinae'') is a freshwater fish dwelling mostly in small to moderate sized streams in areas of swift current. Young and juvenile ''C. carolinae'' can mainly be found in pools, riffles, and other shallow habitats whi ...

(''Cottus carolinae''),

black sculpin The black sculpin (''Cottus baileyi'') is a species of freshawater ray-finned fish belonging to the family Cottidae, the typical sculpins. It is endemic to the United States. Its range includes the extreme upper Clinch and Holston River systems i ...

(''Cottus baileyi''), and

mottled sculpin The mottled sculpin (''Cottus bairdii'') is a species of freshawater ray-finned fish belonging to the family Cottidae, the typical sculpins. This species has a wide but scattered North American distribution. As the name suggests, its coloration ...

(''Cottus bairdi''). This mussel is known as a long term brooder, or bradytictic, meaning it spawns in late summer or fall and releases its larvae in early spring. The main threat to this species is habitat alteration such as channelization and impoundments of waterways, increased

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...

, and pollution. This mussel is propagated in captivity. Many juveniles have been released into appropriate habitat.

References

Natural history of Tennessee Natural history of Virginia Epioblasma Bivalves described in 1834 Taxonomy articles created by Polbot ESA endangered species {{Unionidae-stub