More Information

Additional Information

Pleurobema clava

By Renee Sherman Mulcrone

Geographic Range

The clubshell was historically found in the Ohio, Cumberland and Tennessee River systems and Lake Erie drainages. Within these river systems it was found in the Wabash, Kanawha, Kentucky, Green, Monogahela and Alleghany Rivers. The range of P. clava has been greatly reduced.

In Michigan P. clava is restricted to the St. Joseph River (of the Maumee drainage) in Hillsdale County. (Badra, 2001; Burch, 1975)

Habitat

Pleurobema clava is found in streams and small rivers, in well oxygenated riffles with coarse sand and gravel and little silt. In Michigan, runs where it was found had water currents of 0.06-0.25 meters per second. (Badra, 2001; Watters, 1995)

  • Aquatic Biomes
  • rivers and streams

Physical Description

The northern clubshell is up to 7.6 cm (3 inches) long , and is triangular and elongate in shape. The shell is usually fairly thick, and compressed to moderately inflated. The anterior end is rounded, the posterior end bluntly pointed. The dorsal margin is curved and slanted to the posterior end and the ventral margin is straight to slightly curved.

Umbos are low, being raised only slightly above the hinge line, and are situated at or near the anteriror end. The beak sculpture has concentric ridges at the tip of the umbo, and is not always visible.

The periostracum (outer shell layer) is yellow-brown with prominent broken green rays. Older specimens tend to be more brown or black.

On the inner shell, the left valve has two pseudocardinal teeth, which are small, triangular, serrated and erect. The two lateral teeth are straight to slightly curved, thin, and moderately long. The right valve has one large, erect triangular serrated pseudocardinal tooth and one lateral tooth that is also straight to slightly curved, thin and moderately long.

The beak cavity is shallow to moderately deep. The nacre is white and iridescent at the posterior end.

In Michigan, this species can be confused with the ellipse or the Wabash pigtoe. The ellipse is more compressed and has a more broadly rounded anterior end. The Wabash pigtoe lacks green rays and is also not as wedge-shaped as the clubshell. (Cummings and Mayer, 1992; Watters, 1995)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    7.6 (high) cm
    2.99 (high) in

Development

Fertilized eggs are brooded in the marsupia (water tubes) up to 11 months, 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 a glochidium, usually within a few hours. The glochidia 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)

Reproduction

Age to sexual maturity for this species is unknown. Unionids are gonochoristic (sexes are separate) and viviparous. The glochidia, which are the larval stage of the mussels, are released live from the female after they are fully developed.

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 internally fertilized in the suprabranchial chambers, then pass into water tubes of the gills, where they develop into glochidia.

Pleurobema clava is a short-term brooder. Gravidity has not been recorded, so general spawning time is unknown. (Lefevre and Curtis, 1912; Watters, 1995)

  • Breeding interval
    The clubshell breeds once in the warmer months of the year.
  • Breeding season
    In Michigan, the breeding season is unknown.

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

Lifespan/Longevity

The clubshell can live up to 50 years. (Badra, 2001)

  • Range lifespan
    Status: wild
    50 (high) years

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 P. clava is found buried under the substrate. (Watters, 1995)

Communication and Perception

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.

Mussels are heterothermic, and therefore are sensitive and responsive to temperature.

Unionids in general may have some form of chemical reception to recognize fish hosts. How the clubshell recognizes and/or attracts its fish host is unknown.

Glochidia respond to touch, light and some chemical cues. In general, when touched or a fluid is introduced, they will respond by clamping shut. (Arey, 1921; Badra, 2001; Brusca and Brusca, 2003; Watters, 1995)

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.

The parasitic glochidial stage absorbs blood and nutrients from hosts after attachment. Mantle cells within the glochidia feed off of the host’s tissue through phagocytocis. (Arey, 1921; Meglitsch and Schram, 1991; Watters, 1995)

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)

Ecosystem Roles

Fish hosts are determined by looking at both lab metamorphosis 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.

In lab trials, Pleurobema clava glochidia metamorphosed on the central stoneroller, striped shiner, logperch and blackside darter. (O'Dee and Watters, 2000)

Species Used as Host

Economic Importance for Humans: Positive

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

Economic Importance for Humans: Negative

There are no significant negative impacts of mussels on humans.

Conservation Status

Pleurobema clava is a federally Endangered species in the United States. The IUCN Red List considers this species Critically Endangered. The range of the clubshell has probably been reduced about 95% and this species is likely sensitive to siltation. (Badra, 2001)

Contributors

Renee Sherman Mulcrone (author).

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

detritivore

an animal that mainly eats decomposed plants and/or animals

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

filter-feeding

a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.

freshwater

mainly lives in water that is not salty.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

parasite

an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death

phytoplankton

photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)

planktivore

an animal that mainly eats plankton

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

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

Badra, P. 2001. Special animal abstract for Pleurobema clava (northern clubshell). Lansing, Michigan: Michigan Natural Features Inventory. Accessed October 10, 2005 at http://web4.msue.msu.edu/mnfi/abstracts/aquatics/Pleurobema_clava.pdf.

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.

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.

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.

Meglitsch, P., F. Schram. 1991. Invertebrate Zoology, Third Edition. New York, NY: Oxford University Press, Inc.

O'Dee, S., G. Watters. 2000. New or confirmed host identifications for ten freshwater mussels. Freshwater Mollusk Symposium Proceedings: 77-82.

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

Parmalee, P. 1967. The fresh-water mussels of Illinois. Springfield, Illinois: Illinois State Museum Popular Science Series No. 8. 108 pp.

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

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.

Search

Navigation Links

Information
Specimens
Maps
Classification

Classification