{{Short description|Species of bivalve}} {{Speciesbox | name = Oyster mussel | image = Epioblasma capsaeformis.jpg | image_caption = | status = EN | status_system = IUCN3.1 | status_ref = <ref name="iucn status 17 November 2021">{{cite iucn |author=Cummings, K. |author2=Cordeiro, J. |date=2012 |title=''Epioblasma capsaeformis'' |volume=2012 |article-number=e.T7866A3143774 |doi=10.2305/IUCN.UK.2012-1.RLTS.T7866A3143774.en |access-date=17 November 2021}}</ref> |status2=LE |status2_system=ESA | status2_ref=<ref name=ecos>{{cite web|url=https://ecos.fws.gov/ecp/species/2099|title=Oyster mussel (''Epioblasma capsaeformis'')|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service|access-date=5 April 2023}}</ref><ref>{{Federal Register|62|1647}}</ref> | genus = Epioblasma | species = capsaeformis | authority = ([[Isaac Lea|I. Lea]], 1834) | synonyms = ''Dysnomia capsaeformis'' I. Lea, 1834 }}

The '''oyster mussel''' ('''''Epioblasma capsaeformis''''') is a rare [[species]] of [[freshwater mussel]] in the family [[Unionidae]]. This [[Aquatic animal|aquatic]] [[bivalve]] [[mollusk]] is native to the [[Cumberland River|Cumberland]] and [[Tennessee River]] systems of [[Kentucky]], [[Tennessee]], [[Alabama]], and [[Virginia]] in the United States.<ref name=":0">{{Cite book|title=The freshwater mussels of Tennessee|last=E.|first=Bogan, Arthur|last2=Farms|first2=American Pearl|date=1998|publisher=University of Tennessee Press|isbn=1-57233-013-9|oclc=37980671}}</ref> It has been [[local extinction|extirpated]] from the states of [[Georgia (U.S. state)|Georgia]]<ref name=tnc>[http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Epioblasma+capsaeformis ''Epioblasma capsaeformis''.] {{Webarchive|url=https://web.archive.org/web/20071003223133/http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Epioblasma+capsaeformis |date=2007-10-03 }} The Nature Conservancy.</ref> and [[North Carolina]].<ref name=nc>USFWS. [http://www.fws.gov/nc-es/mussel/oystermuss.html Oyster mussel in North Carolina.]</ref> It is a federally listed [[endangered species]] of the United States.<ref name=ecos/>

This mussel was once widely distributed<ref name=five>USFWS. [http://ecos.fws.gov/docs/five_year_review/doc3774.pdf ''Epioblasma capsaeformis'' Five-year Review.] July 2011</ref> and common.<ref name=tnc/> It has declined 80% from its historical abundance.<ref name="iucn status 17 November 2021" /> It is now extirpated from the Cumberland River system and the main artery of the Tennessee River. It remains in the [[Nolichucky River]] of Tennessee and the [[Clinch River]] in Tennessee and Virginia.<ref name=five/> Specimens once classified as this species that remain in the [[Duck River (Tennessee)|Duck River]] in Tennessee have now been classified as a separate species, ''[[Epioblasma ahlstedti]]''.<ref>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.</ref><ref name=jones>Jones, J. W., et al. (2006). [https://archive.today/20130415202552/http://mollus.oxfordjournals.org/content/72/3/267.short 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.</ref>

This mussel is elliptical or obovate in shape and reaches a maximum length of 70&nbsp;mm. The posterior end of males protrudes slightly, while females are more rounded. The [[periostracum]] is sunshiny, yellowish green, with green rays over the entire shell. The [[nacre]] color is bluish-white to creamy.<ref name=":0" /> [[File:Nolichucky River oyster mussel displaying lure 11 June 2025.png|thumb|left|A gravid female oyster mussel in the [[Nolichucky River]] in eastern [[Tennessee]] displays a vivid blue lure to attract fish into whose gills she will release her parasitic larvae.]] Like other freshwater mussels, this species is reproduces by releasing its larvae, termed [[glochidium|glochidia]], which lodge in the gills of fish to develop into juvenile mussels.<ref name="vincie">Vincie, M. E. (2008) [http://hdl.handle.net/10919/36396 Development of a suitable diet for endangered juvenile oyster mussels ''Epioblasma capsaeformis'' (Bivalvia: Unionidae) reared in a captive environment.] Master's Thesis. Virginia Tech.</ref> Host fish species for this mussel include [[Etheostoma vulneratum|wounded darter]] (''Etheostoma vulneratum''), [[Etheostoma rufilineatum|redline darter]] (''E. rufilineatum''), [[Etheostoma camarum|bluebreast darter]] (''Etheostoma camarum''), [[Percina sciera|dusky darter]] (''Percina sciera''), [[Cottus carolinae|banded sculpin]] (''Cottus carolinae''), [[Cottus baileyi|black sculpin]] (''Cottus baileyi''), and [[Cottus bairdi|mottled sculpin]] (''Cottus bairdi'').<ref name="five" /> 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.<ref name=":0" />

The main threat to this species is habitat alteration such as [[River engineering#Channelization|channelization]] and [[dam|impoundments]] of waterways, increased [[silt]], and pollution.<ref name=tnc/>

This mussel is propagated in captivity.<ref name=vincie/> Many juveniles have been released into appropriate habitat.<ref name=five/>

==References== {{Reflist}}

{{Taxonbar|from=Q308039}}

[[Category:Natural history of Tennessee]] [[Category:Natural history of Virginia]] [[Category:Epioblasma]] [[Category:Bivalves described in 1834]] [[Category:Taxonomy articles created by Polbot]] [[Category:ESA endangered species]]

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