Creature of the Month

Giant Mussel
(Pinna nobilis)

Used with Permission
www.thais.it

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The rare giant mussel, Pinna nobilis, is found only in the
Mediterranean Sea. It is one of the largest bivalves in the world,
growing to 120 cm long. The mussels can live for as long as 20 years.
It sticks up out of the sea bed so is easily seen when diving, once
you know what to look for. 

Pinna nobilis has been assessed by the European Union as being in
need of special protection (EC Habitats Directive). This means that
it is illegal to kill or disturb the species. However, a recent Greek
study found many individuals were killed by fishing. The mussels were
poached exclusively by free-divers and fishing mortality was
practically zero at depths below 9 m, where the visibility was very
bad. Because of this large individuals were restricted to deeper
areas.

In another study, this time off Italy, divers found that the giant
mussels were managing to hold their own, in spite of all the
difficulties of a degraded and heavily polluted environment and the
damages of illegal fishing.

Depending on area, the mussels live between about depths of 3 and 60
m. In the Italian study divers didn't find any below 16 m. In the
Adriatic Sea, they are found down to 30 m. They live singly, not in
large groups like the mussels we are used to. At best the Italian
study found only one every 1.4 hectares (3.5 acres).

The giant bivalve lives on soft bottoms: sand, seagrass meadows and
mud. If you find what looks like a small specimen growing on a rock
it is probably not P. nobilis but the more common P. rudis.

References: 

Environ Monit Assess 2007; 131:339-47
<http://journals.elsevierhealth.com/medline/record/MDLN.17171265>

Marine Biology 2007; DOI: 10.1007/s00227-007-0781-2
<http://www.springerlink.com/content/6g1q01q6v3270182/>

European Council Directive 92/43/EEC of 21 May 1992 on the
conservation of natural habitats and of wild fauna and flora
<http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31992L0043:EN:HTML>

Reprinted with permission:
Copyright SCUBA Travel - http://www.scubatravel.co.uk/