''Dromus dromas'', the dromedary pearlymussel or dromedary naiad, 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 ...

of freshwater mussel in the family Unionidae. 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 in the United States, where it has experienced a large population decline. 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 is yellow-green in color with interrupted green rays on the 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 ...

is white, pink, or reddish. The species got its name from the distinctive hump on the shell of larger individuals.USFWS
''Dromus dromas'' Recovery Plan.
July 1984. This species lives in clear, clean, fast-flowing water. It cannot tolerate water of poor quality, for example, water with

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 ...

.''Dromus dromas''.
The Nature Conservancy. Like other freshwater mussels, this species reproduces by releasing larvae called glochidia into the water. The glochidia are eaten by fish and lodge in the fish's gills, where they develop into juvenile mussels. Fish hosts for this mussel species include

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''),

greenside darter The greenside darter (''Etheostoma blennioides'') 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 inhabits swift ...

(''Etheostoma blennioides''),

fantail darter The fantail (''Etheostoma flabellare'') 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 widely distributed acro ...

(''Etheostoma flabellare''), snubnose darter (''Etheostoma simoterum''), tangerine darter (''Percina aurantiaca''), blotchside logperch (''Percina burtoni''), logperch (''Percina caprodes''),

channel darter The channel darter (''Percina copelandi'') 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 native to North Amer ...

(''Percina copelandi''),

gilt darter The gilt darter (''Percina evides'') 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 can be found in a number of st ...

(''Percina evides''), and Roanoke darter (''Percina roanoka''). This species was historically one of the most common mussels in the Tennessee River. Now only old individuals can be found there. The species has been reduced to no more than 4 populations. It has been extirpated from the wild in the state of

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 ...

, but it has been reintroduced there. The only remaining reproducing populations occur in the Clinch and Powell Rivers. Reproducing populations remain in under 10% of the mussel's historical range, and the populations are disjunct.Jones, J. W., et al. (2004)
Life history and propagation of the endangered dromedary pearlymussel (''Dromus dromas'') (Bivalvia: Unionidae).
''J N Am Benthol Soc'' 23(3) 515-25. Factors contributing to its decline include the

impoundment Impoundment may refer to: Water control * The result of a dam, creating a body of water ** A reservoir, formed by a dam ** Coal slurry impoundment, a specialized form of such a reservoir used for coal mining and processing * Impounded dock, an enc ...

of waterways, increased silt, and pollution from

sewage Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from residenc ...

coal mining Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from ...

, and

oil and gas drilling An oil well is a drillhole boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas may ...

References

{{Taxonbar, from1=Q307710, from2=Q10268818 Molluscs of the United States Unionidae Bivalves described in 1834 ESA endangered species Taxonomy articles created by Polbot Taxa named by Isaac Lea