Fan mussel
Atrina fragilis
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
This 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