Atrina fragilis

Taxobox
name = Fan mussel


image_width =
regnum = Animalia
phylum = Mollusca
classis = Bivalvia
ordo = Pterioida
familia = Pinnidae
genus = "Atrina"
species = "A. fragilis"
binomial = "Atrina fragilis"
binomial_authority = (Pennant,1777)
synonyms = "Pinna fragilis"The fan mussel, "Atrina fragilis", is a large saltwater clam or marine bivalve mollusc in the family Pinnidae, the pen shells.

The fan mussel is one of the largest (30 to 48 cm long) European bivalve molluscs. It is one of the rarest species of marine mollusk in the United Kingdom of Great Britain and Northern Ireland (UK).

The shell of the fan mussel tapers to a point at the umbos, and is very brittle. It is yellowish to dark brown with blackish patches. The two valves are equal and triangular in outline, with prominent gapes. The shell surface has a sculpture of concentric lines and 8 to 12 ribs, which may have fluted spines. Shells can reach 48 cm in length, and the largest individuals may be 10 to 12 years old.

This species lives with the narrow half of its shell anchored in the sediment, but the large part of the fragile shell protrudes from the sea floor. Thus, unfortunately it is vulnerable to fishing. The species is also vulnerable to industrial activity.

The shells are anchored to the sand by fine gold-coloured silk produced by special glands. This silk or "byssus" are fine threads which historically was used to make special royal fabrics. This was called "Pinna silk" or sea silk although the species more frequently used was "Pinna nobilis".

The fan mussel is a UK Priority Species for conservation.

References

* Anon, 1999 Atrina fragilis (a fan shell). Species Action Plan. In UK Biodiversity Group. Tranche 2 Action Plans. English Nature for the UK Biodiversity Group, Peterborough
* Simunovic, A, Piccinetti, C., Bartulovic, M, and Grubelic, I 2001 Distribution of Atrina fragilis (Pennant, 1777) (Pinnidae, Mollusca Bivalvia) in the Adriatic Sea. Acta Adriatica 42(1): 49-59
* Woodward F R 1985. The Fan-mussel, Pinna fragilis Pennant in Scotland. Glasgow Naturalist 21: 63-69.

External links

* [http://www.ukbap.org.uk/UKPlans.aspx?ID=123 U.K. Biodiversity Action Plan]
* [http://animaldiversity.ummz.umich.edu/site/accounts/classification/Atrina_fragilis.html Atrinia fragilis on Animal Diversity Web]
* [http://www.habitas.org.uk/priority/species.asp?item=40786 Priority species in Northern Ireland]
* [http://www.marlin.ac.uk/species/adult_distrib_Atrinafragilis.htm Distribution in Britain and Ireland]