Animal Diversity Web

Ge­o­graphic Range

Mainly an At­lantic coast species, the east­ern el­l­lip­tio is found in the Apalachicola river sys­tem, Al­tamaha River sys­tem of Geor­gia north to the St. Lawrence River sys­tem of Canada. In the In­te­rior Basin it is found west to Lake Su­pe­rior and within the Hud­son Bay drainage.

In Michi­gan E. com­planata is found from Cheboy­gan County north through the upper penin­sula. In the lower penin­sula the south­ern­most records were from Lake Huron. One his­tor­i­cal record was from the Clin­ton River. (Burch, 1975; Mat­te­son, 1948a; Mat­te­son, 1948b)

• Biogeographic Regions
• nearctic
  • native

Habi­tat

The east­ern el­lip­tio is mainly found in sta­ble shoals of lakes or river-lakes in the north­ern part of the lower penin­sula and the upper penin­sula. It was most abun­dant in sub­strates com­posed of clay mixed with marl and fine sand, but rarely in mud. Depths where it seemed most com­mon were one to 1.6 m (3 to 5 feet). (Mat­te­son, 1948c; van der Schalie, 1938)

• Habitat Regions
• freshwater

• Aquatic Biomes
• rivers and streams

• Range depth

  1.6 (high) m

  5.25 (high) ft

Phys­i­cal De­scrip­tion

The east­ern el­lip­tio is up to 12.5 cm (5 inches) long , and is quadrate or rec­tan­gu­lar in shape. The shell is heavy and com­pressed with an an­gu­lar pos­te­rior ridge and promi­nent pos­te­rior slope. The an­te­rior end is rounded, the pos­te­rior end rounded to bluntly pointed. The dor­sal mar­gin is straight and the ven­tral mar­gin is straight to slightly curved.

Umbos are low, being raised only slightly above the hinge line. The beak sculp­ture has 5-6 ridges.

The pe­rios­tracum (outer shell layer) is tan or brown, some­times with green rays. Older spec­i­mens tend to be more brown or black.

On the inner shell, the left valve has two pseudo­car­di­nal teeth, which are tri­an­gu­lar and rough. The two lat­eral teeth are straight to slightly curved and mod­er­ately long. The right valve has one tri­an­gu­lar, rough pseudo­car­di­nal tooth, and one straight to slightly curved, long, lat­eral tooth.

The beak cav­ity is shal­low. The nacre is pur­ple, rose-col­ored or white.

In Michi­gan, this species can be con­fused with the spike. The east­ern el­lipse is slightly more rhom­boidal, more com­pressed, and has a slightly more promi­nent pos­te­rior ridge. (Cordeiro, 2003; Nedeau, et al., 2000)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike

• Range length

  12.5 (high) cm

  4.92 (high) in

De­vel­op­ment

Fer­til­ized eggs are brooded in the mar­su­pia (water tubes) up to one months, de­pend­ing on en­vi­ron­men­tal con­di­tions, where they de­velop into lar­vae, called glochidia. The glochidia are then re­leased into the water where they must at­tach to the gill fil­a­ments and/or gen­eral body sur­face of the host fish. After at­tach­ment, ep­ithe­lial tis­sue from the host fish grows over and en­cap­su­lates the glochid­ium, usu­ally within a few hours. The glochida then meta­mor­phoses into a ju­ve­nile mus­sel within a few days or weeks. After meta­mor­pho­sis, the ju­ve­nile is sloughed off as a free-liv­ing or­gan­ism. Ju­ve­niles are found in the sub­strate where they de­velop into adults. (Arey, 1921; Lefevre and Cur­tis, 1910; Mat­te­son, 1948c)

• Development - Life Cycle
• metamorphosis

Re­pro­duc­tion

In gen­eral, ga­me­to­ge­n­e­sis in union­ids is ini­ti­ated by in­creas­ing water tem­per­a­tures. The gen­eral life cycle of a unionid, in­cludes open fer­til­iza­tion. Males re­lease sperm into the water, which is taken in by the fe­males through their res­pi­ra­tory cur­rent. The eggs are fer­til­ized in the suprabranchial cham­bers, then pass into water tubes of the gills, where they de­velop into lar­vae, called glochidia. (Lefevre and Cur­tis, 1912; Wat­ters, 1995)

• Key Reproductive Features
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• viviparous

• Breeding season

  In Michigan, the breeding season is mid-July to August.

• Average gestation period

  10 months

Fe­males brood fer­til­ized eggs in their mar­su­pial pouch. The fer­til­ized eggs de­velop into glochidia. There is no parental in­vest­ment after the fe­male re­leases the glochidia.

• Parental Investment
• pre-fertilization
  • provisioning
• pre-hatching/birth
  • provisioning
    • female

Be­hav­ior

Mus­sels in gen­eral are rather seden­tary, al­though they may move in re­sponse to chang­ing water lev­els and con­di­tions. Al­though not thor­oughly doc­u­mented, the mus­sels may ver­ti­cally mi­grate to re­lease glochidia and spawn. Often they are found buried under the sub­strate. (Oesch, 1984)

• Key Behaviors
• parasite
• motile
• sedentary

Com­mu­ni­ca­tion and Per­cep­tion

Three large, dis­tinct gan­glia make up the bi­lat­eral ner­vous sys­tem of a bi­valve. Cere­bro­pleural gan­glia are an­te­rior and give rise to the vis­ceral (gut) gan­glia and pedal (foot) gan­glia.

The mid­dle lobe of the man­tle edge has most of a bi­valve's sen­sory or­gans. Paired sta­to­cysts, which are fluid filled cham­bers with a solid gran­ule or pel­let (a sta­tolity) are in the mus­sel's foot. The sta­to­cysts help the mus­sel with geo­re­cep­tion, or ori­en­ta­tion.

Union­ids in gen­eral may have some form of chem­i­cal re­cep­tion to rec­og­nize fish hosts. Man­tle flaps in the lamp­si­lines are mod­i­fied to at­tract po­ten­tial fish hosts. How the snuff­box at­tracts its main fish host, the log­perch, is un­known. How­ever, the man­tle flaps are dark­ened and may re­sem­ble food for the log­perch.

Glochidia re­spond to both touch, light and some chem­i­cal cues. In gen­eral, when touched or a fluid is in­tro­duced, they will re­spond by clamp­ing shut. (Arey, 1921; Br­usca and Br­usca, 2003; Wat­ters, 1995)

• Communication Channels
• chemical

• Perception Channels
• visual
• tactile
• vibrations
• chemical

Food Habits

In gen­eral, union­ids are fil­ter feed­ers. The mus­sels use cilia to pump water into the in­cur­rent siphon where food is caught in a mucus lin­ing in the demi­branchs. Par­ti­cles are sorted by the labial palps and then di­rected to the mouth.

Mus­sels have been cul­tured on algae, but they may also in­gest bac­te­ria, pro­to­zoans and other or­ganic par­ti­cles. (Wat­ters, 1995)

• Primary Diet
• planktivore
• detritivore

• Plant Foods
• algae
• phytoplankton

• Other Foods
• detritus
• microbes

• Foraging Behavior
• filter-feeding

Pre­da­tion

Union­ids in gen­eral are preyed upon by muskrats, rac­coons, minks, ot­ters, and some birds. Ju­ve­niles are prob­a­bly also fed upon by fresh­wa­ter drum, sheepshead, lake stur­geon, spot­ted suck­ers, red­horses, and pump­kin­seeds.

Unionid mor­tal­ity and re­pro­duc­tion is af­fected by union­i­colid mites and mono­genic trema­todes feed­ing on gill and man­tle tis­sue. Par­a­sitic chi­rono­mid lar­vae may de­stroy up to half the mus­sel gill. (Cum­mings and Mayer, 1992; Wat­ters, 1995)

• Known Predators

  • muskrat, Ondatra zibethicus
  • mink, Neovison vison
  • raccoon Procyon lotor
  • otter, Lontra canadensis
  • turtles, Testudines
  • hellbenders, Cryptobranchus
  • freshwater drum, Aplodinotus grunniens
  • sheepshead, Archosargus probatocephalus
  • lake sturgeon, Acipenser fulvescens
  • shortnosed sturgeon, Acipenser brevirostrum
  • spotted suckers, Minytrema melanops
  • common red-horse, Moxostoma
  • catfish, Siluriformes
  • pumpkinseed, Lepomis gibbosus

Ecosys­tem Roles

Fish hosts are de­ter­mined by look­ing at both lab trans­for­ma­tions and nat­ural in­fes­ta­tions. Look­ing at both is nec­es­sary, as lab trans­for­ma­tions from glochidia to ju­ve­nile may occur, but the mus­sel may not ac­tu­ally in­fect a par­tic­u­lar species in a nat­ural sit­u­a­tion. Nat­ural in­fes­ta­tions may also be found, but glochidia will at­tach to al­most any fish, in­clud­ing those that are not suit­able hosts. Lab trans­for­ma­tions in­volve iso­lat­ing one par­tic­u­lar fish species and in­tro­duc­ing glochidia ei­ther into the fish tank or di­rectly in­oc­u­lat­ing the fish gills with glochidia. Tanks are mon­i­tored and if ju­ve­niles are later found the fish species is con­sid­ered a suit­able host.

Lab meta­mor­pho­sis and nat­ural in­fec­tions of El­lip­tio com­planata have been ob­served for the yel­low perch and the banded kil­li­fish,.

In lab tri­als, El­lip­tio com­planata meta­mor­phosed on the green sun­fish, the large­mouth bass, the or­angespot­ted sun­fish, and the white crap­pie. (Cum­mings and Wat­ters, 2004; Lefevre and Cur­tis, 1912; Mat­te­son, 1948c; Mat­te­son, 1955; Tedla and Fer­nando, 1969; Young, 1911)

• Ecosystem Impact
• parasite

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Mus­sels are eco­log­i­cal in­di­ca­tors. Their pres­ence in a water body usu­ally in­di­cates good water qual­ity.

Con­ser­va­tion Sta­tus

This species is not on any fed­eral or state lists.

• IUCN Red List

  No special status
  More information

• IUCN Red List

  No special status
  More information

• US Federal List

  No special status

• CITES

  No special status

Other Com­ments

El­lip­tio com­planata is syn­onomous with El­lip­tio com­plana­tus.

An de­tailed life his­tory of this species was done by Max Mat­te­son in the early 1940s in north­ern Michi­gan. (Mat­te­son, 1948c)

Con­trib­u­tors

Renee Sher­man Mul­crone (au­thor).

Ref­er­ences

Arey, L. 1921. An ex­per­i­men­tal study on glochidia and the fac­tors un­der­ly­ing en­cyst­ment. J. Exp. Zool., 33: 463-499.

Br­usca, R., G. Br­usca. 2003. In­ver­te­brates. Sun­der­land, Mass­a­chu­setts: Sin­auer As­so­ci­ates, Inc..

Burch, J. 1975. Fresh­wa­ter unionacean clams (Mol­lusca: Pele­cy­poda) of North Amer­ica. Ham­burg, Michi­gan: Mala­co­log­i­cal Pub­li­ca­tions.

Cordeiro, J. 2003. "Fam­ily Union­idae: Genus El­lip­tio" (On-line). Fresh­wa­ter mus­sels of the New York met­ro­pol­i­tan re­gion and New Jer­sey, A guide to their iden­ti­fi­ca­tion, bi­ol­ogy, and con­ser­va­tion. Ac­cessed Sep­tem­ber 05, 2006 at http://​cbc.​amnh.​org/​mussel/​elliptiogenustext.​html.

Cum­mings, K., C. Mayer. 1992. Field guide to fresh­wa­ter mus­sels of the Mid­west. Cham­paign, Illi­nois: Illi­nois Nat­ural His­tory Sur­vey Man­ual 5. Ac­cessed Au­gust 25, 2005 at http://​www.​inhs.​uiuc.​edu/​cbd/​collections/​mollusk/​fieldguide.​html.

Cum­mings, K., G. Wat­ters. 2004. "Mus­sel/Host Data Base" (On-line). Mol­luscs Di­vi­sion of the Mu­seum of Bi­o­log­i­cal Di­ver­sity at the Ohio State Uni­ver­sity. Ac­cessed Sep­tem­ber 25, 2005 at http://​128.​146.​250.​63/​Musselhost/​.

Lefevre, G., W. Cur­tis. 1912. Ex­per­i­ments in the ar­ti­fi­cial prop­a­ga­tion of fresh-wa­ter mus­sels. Proc. In­ter­nat. Fish­ery Con­gress, Wash­ing­ton. Bull. Bur. Fish­eries, 28: 617-626.

Lefevre, G., W. Cur­tis. 1910. Re­pro­duc­tion and par­a­sitism in the Union­idae. J. Expt. Biol., 9: 79-115.

Mat­te­son, M. 1948. The tax­o­nomic and dis­tri­b­u­tional his­tory of the fresh-wa­ter mus­sel El­lip­tio com­plana­tus (Dill­wyn, 1817). Nau­tilus, 61: 127-132.

Mat­te­son, M. 1948. The tax­o­nomic and dis­tri­b­u­tional his­tory of the fresh-wa­ter mus­sel El­lip­tio com­plana­tus (Dill­wyn, 1817) (con­tin­ued). Nau­tilus, 62: 13-1.

Mat­te­son, M. 1948. Life his­tory of El­lip­tio com­plana­tus (Dill­wyn, 1817). Amer­i­can Mid­land Nat­u­ral­ist, 40: 690-723.

Mat­te­son, M. 1955. Stud­ies on the nat­ural his­tory of the Union­idae. Amer­i­can Mid­land Nat­u­ral­ist, 53: 126-145.

Nedeau, E., M. Mc­Col­lough, B. Swartz. 2000. The fresh­wa­ter mus­sels of Maine. Au­gusta, Maine: Maine Dept. of In­s­land Fish­eries and Wildlife.

Oesch, R. 1984. Mis­souri na­iades, a guide to the mus­sels of Mis­souri. Jef­fer­son City, Mis­souri: Mis­souri De­part­ment of Con­ser­va­tion.

Tedla, S., C. Fer­nando. 1969. Ob­ser­va­tions on the glochidia of Lamp­silis ra­di­ata (Gmelin) in­fest­ing yel­low perch, Perca flavescens (Mitchill) in the Bay of Quinte, Lake On­tario. Cana­dian Jour­nal of Zo­ol­ogy, 47: 705-712.

Wat­ters, G. 1995. A guide to the fresh­wa­ter mus­sels of Ohio. Colum­bus, Ohio: Ohio De­part­ment of Nat­ural Re­sources.

Young, D. 1911. The im­plan­ta­tion of the glochid­ium on the fish. Uni­ver­ity of Mis­souri Bul­letin Sci­ence Se­ries, 2: 1-20.

van der Schalie, H. 1938. The naiad fauna of the Huron River, in south­east­ern Michi­gan. Mis­cel­la­neous Pub­li­ca­tions of the Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan, 40: 1-83.