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The freshwater pearl mussel, scientific name Margaritifera margaritifera, is an endangered species of freshwater mussel, an aquatic bivalve mollusk in the family Margaritiferidae, the freshwater pearl mussels.
The name "freshwater pearl mussel" should not be construed to mean that other freshwater mussels do not harbor pearls or cannot be used as mother of pearl. In fact most cultured pearls today come from Hyriopsis species in Asia, or Amblema species in North America, both members of the related family Unionidae. Pearls are also found in genus unio.
The interior of the shell of this species has thick nacre. The species is capable of making fine quality pearls, therefore it was historically exploited in the search for pearls from wild sources.
Deutsche Post featured Margaritifera margaritifera on a 2002 German € 0.56 postage stamp as part of a series on endangered species of animals .
Group of live Margaritifera margaritifera
in a river bed in Sweden
Subspecies within the species Margaritifera magaritifera include:
- Margaritifera margaritifera margaritifera (Linnaeus, 1758)
- Margaritifera margaritifera parvula (Haas, 1908)
- Margaritifera margaritifera durrovensis Phillips, 1928 - critically endangered subspecies in Ireland. Synonym: Margaritifera durrovensis. This subspecies is mentioned in annexes II and V of Habitats Directive as Margaritifera durrovensis.
The interior of the shell of Margaritifera margaritifera
, showing the nacre
The anatomy of Margaritifera margaritifera
Posterior adductor muscle
Anterior adductor muscle
The hingeline and ligament
The shell's thickest part, the umbo
The native distribution of this species is Holarctic.
- More than half the world's recruiting population exists in Scotland
- North America: eastern Canada and New England at northwestern of the United States
- Continental Europe, including:
- Czech Republic - critically endangered (CR). Listed in Decree for implementation, No. 395/1992 Sb. (Czech code) (in Czech: Vyhláška 395/1992 Sb. ve znění vyhl. 175/2006 Sb.) as Critically Threatened species. It's Conservation status in 2004-2006 is bad (U2) in report for European commission in accordance with Habitats Directive.
- Germany - critically endangered (vom Aussterben bedroht). Listed as strictly protected species in annex 1 in Bundesartenschutzverordnung.
- Great Britain. This species is fully protected in the United Kingdom under the Wildlife and Countryside Act 1981 since 1998 and it has been partly protected according to the section 9(1) already since 1991.
- Ireland - Republic Ireland is estimated to hold 46% of the population in Europe, with the largest population present in the Munster Blackwater Catchment (c. 12,000,000 individuals). The Cladagh (Swanlinbar) river contains one of the largest populations surviving in Northern Ireland, estimated minimum 10,000, confined to a 6 km stretch of undisturbed river in the middle section.
- Lithuania - extinct
- Poland - extinct
- Iberian Peninsula (Portugal and Spain)
- Scandinavian Peninsula (Finland, Norway, rare in Sweden)
- Russian Federation - in the rivers of the White Sea basin of the Arkhangelsk and Murmansk Regions. It is east border of the area of distribution M. margaritifera.