Swan Mussel
(Anodonta cygnea)
This large bivalve mollusc pertains to the Unionidae family.
Distribution
The species is spread throughout Europe, particularly in slow-moving waterways.
Description
A bivalve mollusc with an elongated oval shell, it can grow up to 25 cm. Its state of growth is evident, since concentric circles accumulate on its shell during periods of growth. The inside is instead generally nacreous.
Habitat
It is undoubtedly a very particular species, found in the Reserve in its natural habitat of non-flowing, stagnant water. This mollusc is well established in muddy terrain, sometimes almost completely buried and extending only its siphons for water filtration and respiration. This animal is very adaptable and is also useful. If healthy, it can filter nearly 40 litres of water per hour.
Observation in the Torbiera Reserve
The empty shells of these bivalves can be seen in some secondary canals and at the edge of the ponds. There is no certain data as to whether other species of Unionidae are also present in the Reserve.