Atrina fragilis
Encyclopedia
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 mm long) Europe
an bivalve molluscs. It is one of the rarest species of marine mollusc in the United Kingdom
(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
of the Mediterranean.
The fan mussel is a UK Priority Species for conservation. This species is protected in the United Kingdom under the Wildlife and Countryside Act 1981
from killing and injuring, possession and sale since 1998.
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
bivalve mollusc in the family Pinnidae
Pinnidae
Pinnidae is a family of large saltwater clams sometimes known as pen shells. They are marine bivalve molluscs in the order Pterioida.The shells are fragile and have a long and triangular shape, and in life they are anchored in sediment using a byssus...
, the pen shells.
The fan mussel is one of the largest (30 to 48 mm long) Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
an bivalve molluscs. It is one of the rarest species of marine mollusc in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
(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
Sculpture (mollusc)
The sculpture of a mollusc shell is the three-dimensional ornamentation on the outer surface, as distinct from the basic shape of the shell itself or colouration. Sculpture may be concave as well as convex. Sometimes it has microscopic detail. Sculpture refers to the calcareous outer layer, not the...
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
Byssus
Byssus means both a silky filament by which certain molluscs attach themselves to hard surfaces, and a rare fabric, also called sea silk and its fibre source.-Word:...
are fine threads which historically was used to make special royal fabrics. This was called Pinna silk or sea silk
Sea silk
Sea silk is an extremely fine, rare and valuable fabric produced from the long silky filaments or byssus secreted by a gland in the foot of several bivalve molluscs by which they attach themselves to the sea bed....
, although the species more frequently used was Pinna nobilis
Pinna nobilis
Pinna nobilis, common name the "noble pen shell" is a species of pen shell, a large marine bivalve mollusc in the family Pinnidae, the 'pen shells'....
of the Mediterranean.
The fan mussel is a UK Priority Species for conservation. This species is protected in the United Kingdom under the Wildlife and Countryside Act 1981
Wildlife and Countryside Act 1981
The Wildlife and Countryside Act 1981 is an Act of Parliament in the United Kingdom and was implemented to comply with the Directive 2009/147/EC on the conservation of wild birds...
from killing and injuring, possession and sale since 1998.
External links
- http://www.ukbap.org.uk/UKPlans.aspx?ID=123U.K. Biodiversity Action PlanBiodiversity Action PlanA Biodiversity Action Plan is an internationally recognized program addressing threatened species and habitats and is designed to protect and restore biological systems. The original impetus for these plans derives from the 1992 Convention on Biological Diversity...
] - Atrinia fragilis on Animal Diversity Web
- Priority species in Northern Ireland
- Distribution in Britain and Ireland