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Unionidae

(Family)

Overview

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Unionidae is a family of freshwater mussels, the largest in the order Unionoida, the bivalve mollusks sometimes known as river mussels, naiads, or simply as unionids.1][2]

The range of distribution for this family is world-wide. It is at its most diverse in North America, with about 297 recognised taxa[3][4][5], but China and Southeast Asia also support very diverse faunas.

Freshwater mussels occupy a wide range of habitats, but most often occupy lotic waters, i.e. flowing water such as rivers, streams and creeks.

Life habits

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< p>Unionidae burrow into the substrate, with their posterior margins exposed. They pump water through the incurrent aperture, obtaining oxygen and food.

Unionidae are distinguished by a unique and complex life cycle. Most Unionids are of separate sex (although some species, such as Elliptio complanata, are known to be hermaphroditic). The sperm is ejected from the mantle cavity through the male?s excurrent aperture and taken into the female's mantle cavity through the incurrent aperture. Fertilised eggs move from the gonads to the gills (marsupia) where they further ripen and metamorph into glochidia, the first larval stage. Mature glochidia are released by the female and then attach to the gills, fins or skin of a host fish. A cyst is quickly formed around the glochidia, and they stay on the fish for several weeks or months before they fall off as juvenile mussels which then bury themselves in the sediment.

Reproduction

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Some of the species in the freshwater mussel family, Unionidae, commonly known as pocketbook mussels have evolved a remarkable reproductive strategy. The edge of the female's body that protrudes from the valves of the shell develops into an imitation of a small fish complete with markings and false eyes. This decoy moves in the current and attracts the attention of real fish. Some fish see the decoy as prey, while others see a conspecif ic, i.e. a member of their own species. Whatever they see, they approach for a closer look and the mussel releases huge numbers of larvae from her gills, dousing the inquisitive fish with her tiny, parasitic young. These glochidia larvae are drawn into the fish's gills where they attach and trigger a tissue response that forms a small cyst in which the young mussel resides. It feeds by breaking down and digesting the tissue of the fish within the cyst.[6]

Genera

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Widespread

Africa

Central America and Mexico

Eastern Asia

Europe

India

Middle East

New Guinea

North America

Fossilization and taphonomic implications

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In large enough quantities, unionid shells can have enough of an impact on environmental conditions to effect the ability of organic remains in the local environment to fossilize.[7] For example, in the Dinosaur Park Formation, fossil hadrosaur eggshell is rare.[7] This is because the breakdown of tannins from local coniferous vegetation would have caused the ancient waters to become acidic.[7] Eggshell fragments are present in only two microfossil sites, both of which are predominated by the preserved shells of invertebrate life, including unionids.[7] It was the slow dissolution of these shells releasing calcium carbonate into the water that raised the water's pH high enough to prevent the eggshell fragments from dissolving before they could be fossilized.[7]

in which the young mussel resides. It feeds by breaking down and digesting the tissue of the fish within the cyst.[6]

Genera

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Widespread

Africa

Central America and Mexico

Eastern Asia

Europe

India

Middle East

New Guinea

North America

Fossilization and taphonomic implications

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In large enough quantities, unionid shells can have enough of an impact on environmental conditions to effect the ability of organic remains in the local environment to fossilize.[7] For example, in the Dinosaur Park Formation, fossil hadrosaur eggshell is rare.[7] This is because the breakdown of tannins from local coniferous vegetation would have caused the ancient waters to become acidic.[7] Eggshell fragments are present in only two microfossil sites, both of which are predominated by the preserved shells of invertebrate life, including unionids.[7] It was the slow dissolution of these shells releasing calcium carbonate into the water that raised the water's pH high enough to prevent the eggshell fragments from dissolving before they could be fossilized.[7]

References

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  1. ^ Unionidae.  Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=160333 on 4 January 2012.
  2. ^ Huber, Markus (2010). Compendium of Bivalves. A Full-color Guide to 3'300 of the World's Marine Bivalves. A Status on Bivalvia after 250 Years of Research. Hackenheim: ConchBooks. pp. 901 pp. + CD. ISBN 978-3-93976 7-28-2. 
  3. ^ Williams, J. D, M. L. Warren, K. S. Cummings, J. L. Harris, and R. J. Neves (1993). "Conservation Status of Freshwater Mussels of the United States and Canada". Fisheries 18 (9): 6?22. doi:10.1577/1548-8446(1993)018<0006:CSOFMO>2.0.CO;2. ISSN 1548-8446. 
  4. ^ Burch, John B.. 1975. Freshwater unionacean clams (Mollusca: Pelecypoda) of North America. Biota of Freshwater Ecosystems, Identification Manual No. 11. U.S. Gov. Printing Office. 114p.
  5. ^ Heard, William H. 1979. Identification Manual of the Freshwater Clams of Florida. Fla. Dept. Environmental Regulation, Technical Series 4(2): 1-83.
  6. ^ Piper, Ross (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
  7. ^ a b c d e Tanke, D.H. and Brett-Surman, M.K. 2001. Evidence of Hatchling and Nestling-Size Hadrosaurs (Reptilia:Ornithischia) from Dinosaur Provincial Park (Dinosaur Park Formation: Campanian), Alberta, Canada. pp. 206-218. In: Mesozoic Vertebrate Life?New Research Inspired by the Paleontology of Philip J. Currie. Edited by D.H. Tanke and K. Carpenter. Indiana University Press: Bloomington. xviii + 577 pp.

External links

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Taxonomy

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The Family Unionidae is a member of the Superfamily Unionacea. Here is the complete "parentage" of Unionidae:

The Family Unionidae is further organized into finer groupings including:

Genera

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Acanthais

[more]

Acreuciroa

[more]

Actinonaias

Actinonaias is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Acuticosta

[more]

Afronaia

[more]

Alasmidonta

Alasmidonta is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Amblema

Amblema is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Amphinaias

[more]

Anemina

[more]

Anodonta

Anodonta is a genus of medium-sized to large freshwater mussels, aquatic bivalve molluscs in the family Unionidae. [more]

Anodontoides

Anodontoides is a genus of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels. [more]

Arcidens

[more]

Arconaia

[more]

Arkansia

Arkansia is a monotypic genus of freshwater mussels in the family Unionidae, the river mussels. The sole species in the genus is Arkansia wheeleri. Its common names are the Ouachita rock pocketbook and Wheeler's pearly mussel. The genus was named for the state of Arkansas, where the mussel was first discovered. This is a federally listed endangered species of the United States. [more]

Barynaias

[more]

Brazzaea

[more]

Caelatura

A Genus in the Kingdom Animalia. [more]

Cafferia

[more]

Canthyria

[more]

Carunculina

[more]

Chamberlainia

[more]

Coelatura

Coelatura is a genus of bivalve in the Unionidae family. It contains the following species: [more]

Conchodromus

Contradens

[more]

Crenodonta

Cristaria

A genus in the Kingdom Animalia. [more]

Cuneopsis

[more]

Cyclonaias

Cyclonaias is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Cyprogenia

Cyprogenia is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae. [more]

Cyrtonaias

[more]

Disconaias

Disconaias is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Dromus

Dromus is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae. [more]

Dysnomia

A Genus in the Kingdom Animalia. [more]

Ellipsaria

Ellipsaria is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Elliptio

Elliptio is a genus of medium-sized to large-sized freshwater mussels, aquatic bivalve mollusks in the family Unionidae, commonly known as the unionids, freshwater mussels or naiads. In contrast with many other groups of American unionidae, the Elliptio reach their greatest diversity in the Atlantic draining rivers of Georgia and the Carolinas, and large parts of Florida. One species ranges north into New England and southern Canada, and two occur in the interior Mississippi drainages. Most Elliptio species have elongate shells, with silvery or purplish interior nacre beneath a thick periostracum, and few reach large size or thickness. [more]

Elliptoideus

Elliptoideus is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Elongaria

[more]

Ensidens

[more]

Epioblasma

Epioblasma is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. Most of the species in this genus have been lost in modern times, and the entire genus is threatened with the possibility of extinction. [more]

Friersonia

[more]

Fusconaia

Fusconaia is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae. [more]

Glebula

[more]

Gonidea

[more]

Grandidieria

[more]

Hamiota

Harmandia

[more]

Hemistena

[more]

Hyriopsis

[more]

Iheringella

[more]

Indonaia

[more]

Inversidens

[more]

Juvenile

[more]

Lamellidens

[more]

Lamillidens

[more]

Lamproscapha

[more]

Lamprotula

[more]

Lampsilis

Lampsilis is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae,the river mussels. [more]

Lanceolaria

[more]

Lasmigona

Lasmigona is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae. [more]

Leguminaia

[more]

Lemiox

Lemiox is a of aquatic bivalves, freshwater mussels in the family Unionidae. [more]

Lepidodesma

Leptodea

Leptodea is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Lexingtonia

Lexingtonia is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Ligumia

Ligumia is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae. [more]

Medionidus

Medionidus is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae. [more]

Microcondylaea

[more]

Modellnaia

Mweruella

Myodora

[more]

Nephronaias

[more]

Nipponoclava

[more]

Nitia

Nyassunio

Obliquaria

[more]

Obovaria

Obovaria is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Oxynaia

Parreysia

[more]

Pegias

Pegias is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae. [more]

Pegius

[more]

Physunio

[more]

Pilsbryoconcha

Plectomerus

[more]

Plesielliptio

Plethobasus

Plethobasus is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Pleurobema

Pleurobema is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Pleuronaia

Popenaias

Popenaias is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Popenais

[more]

Potamilus

Potamilus is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Potomida

Pressidens

[more]

Prisodontopsis

Proparreysia

Proptera

[more]

Protunio

Pseudanodonta

[more]

Pseudodon

[more]

Pseudodontopsis

Pseudospatha

Pseudospatha is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Pseudunio

Psoronaias

[more]

Ptychobranchus

Ptychobranchus is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae. [more]

Pygandon

[more]

Pyganodon

Pyganodon is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Quadrula

Quadrula is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae native to rivers of the American Midwest and mid-south. All have thick nacreous shells with well-developed hinge teeth, many also with external shell sculpturing of nodules or lumps. [more]

Quincuncina

Quincuncina is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Rectidens

Rhombuniopsis

Scabies

Scabies (from Latin: , "to scratch"), known colloquially as the seven-year itch, is a contagious skin infection that occurs among humans and other animals. It has been classified by the WHO as a water-related disease. It is caused by a tiny and usually not directly visible parasite, the mite Sarcoptes scabiei, which burrows under the host's skin, causing intense allergic itching. The infection in animals (caused by different but related mite species) is called sarcoptic mange. [more]

Schistodesmus

[more]

Simpsonaias

Simpsonaias is aa of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Sinanodonta

[more]

Solenaia

Strophitus

Strophitus is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Symphynota

[more]

Theliderma

Toxolasma

Toxolasma is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae, the river mussels. [more]

Trapezoides

Trapezoideus

[more]

Tritigonia

Tritogonia

[more]

Truncilla

[more]

Uniandra

Unio

Unio can refer to: [more]

Uniomerus

[more]

Utterbackia

[more]

Venustaconcha

[more]

Villosa

Villosa is a of freshwater mussels, aquatic bivalve mollusks in the family Unionidae. [more]

At least 21 species and subspecies belong to the Genus Villosa.

More info about the Genus Villosa may be found here.

References

[ Back to top ]
  1. ^ Unionidae.  Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=160333 on 4 January 2012.
  2. ^ Huber, Markus (2010). Compendium of Bivalves. A Full-color Guide to 3'300 of the World's Marine Bivalves. A Status on Bivalvia after 250 Years of Research. Hackenheim: ConchBooks. pp. 901 pp. + CD. ISBN 978-3-939767-28-2. 
  3. ^ Williams, J. D, M. L. Warren, K. S. Cummings, J. L. Harris, and R. J. Neves (1993). "Conservation Status of Freshwater Mussels of the United States and Canada". Fisheries 18 (9): 6?22. doi:10.1577/1548-8446(1993)018<0006:CSOFMO>2.0.CO;2. ISSN 1548-8446. 
  4. ^ Burch, John B.. 1975. Freshwater unionacean clams (Mollusca: Pelecypoda) of North America. Biota of Freshwater Ecosystems, Identification Manual No. 11. U.S. Gov. Printing Office. 114p.
  5. ^ Heard, William H. 1979. Identification Manual of the Freshwater Clams of Florida. Fla. Dept. Environmental Regulation, Technical Series 4(2): 1-83.
  6. ^ Piper, Ross (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
  7. ^ a b c d e Tanke, D.H. and Brett-Surman, M.K. 2001. Evidence of Hatchling and Nestling-Size Hadrosaurs (Reptilia:Ornithischia) from Dinosaur Provincial Park (Dinosaur Park Formation: Campanian), Alberta, Canada. pp. 206-218. In: Mesozoic Vertebrate Life?New Research Inspired by the Paleontology of Philip J. Currie. Edited by D.H. Tanke and K. Carpenter. Indiana University Press: Bloomington. xviii + 577 pp.

Sources

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Last Revised: August 24, 2012
2012/08/24 13:45:35