Fan mussel

Atrina fragilis


Fan Mussel © Nigel Mortimer

The fan mussel is a large triangular mussel, with a thin, easily broken shell.  It can grow to nearly 50cm long, making it one of the largest shells found in British waters.   

The fan mussel lives in areas of soft seabed, with up to two thirds of its length buried in the mud, sand or gravel.  It also uses fine threads, called byssus threads, to anchor itself to small stones or shell fragments.

Fan mussels can be found around the low water mark on coasts sheltered from the waves, but they can also live at depths as great as 400m below the surface.

The fan mussel is scarce, and considered to be one of the most endangered animals of its kind in UK waters.  Fan mussels used to occur in beds containing large numbers of the animals, but recent records only report them singly or in small groups.  They are also recorded from fewer places than was the case in the past.

Once the populations of fan mussels have been reduced, it is hard for them to recover because without sufficient numbers of other animals nearby, their eggs cannot be fertilised effectively.  The main threats to the remaining fan mussels are beam trawling and scallop dredging, although they may also be harmed by pollution or other changes in water quality.


European distribution

In the UK, the fan mussel is found mostly in the south-west of England and in western and northern Scotland.  Its range extends as far as the Iberian Peninsula of south-west Spain and Portugal, and into the Adriatic Sea.


Conservation status/need

  • Fan Mussel FactThis is a UK BAP Priority Species (BAP species are now Species of Principal Importance/Priority Species).
  • Species of principal importance for the purpose of conservation of biodiversity under the Natural Environment and Rural Communities Act 2006
  • Protected under Schedule 5 of the Wildlife and Countryside Act 1981


Further information

Biodiversity Action Reporting System

Marine Life Information Network

World Register of Marine Species

JNCC - UK BAP Priority Species and Habitats