Pinna nobilis mussel pen Noble pen shell fan mussel intotheblue.it
Pinna nobilis (Linnaeus 1758), commonly known as mussel pen, Noble pen shell or fan mussel, is the largest bivalve in the Mediterranean Sea. It can reach one meter in length. Its collection is prohibited. In any case, despite being edule, being a mollusc filter, it is extremely risky to eat it as it accumulates absorbing them from the sea large amounts of pollutants and pathogens. For this reason it has been used as an indicator of marine pollution (also nuclear at La Maddalena).
Distribution and habitat
Endemic to the Mediterranean Sea, it is often located in the middle of Posidonia oceanica meadows, from a few meters up to 40 meters deep. It was reported in 2008 the reappearance also in correspondence of the Lagoon of Grado, Marano Lagoon and Venetian Lagoon, as apparent consequence of the artificial reefs of the MOSE project [: in the years 1950-’60 it had witnessed its progressive disappearance due to the lagoon pollution caused by discharges from the Marghera industrial center.
It is a sessile organism that lives fixed with the pointed part of its triangular shell in the sand or in the rock.
To feed and breathe, pump the water into the mantle cavity using an inhalation siphon and then emit it through an exhalation. The valves have a rounded back margin and have about twenty radial ribs with channel-shaped flakes. The color is brown with lighter scales; the interior is brown and shiny with the mother-of-pearl front. They can live more than 20 years and reach one meter in length, but the average size of the shell of an adult is around 65 cm. It has a fairly rapid development in the first years of life, on average 10 cm per year; reached sexual maturity, around 40 cm, the growth slows down and settles on about 10 cm every 3 years.
Inside it sometimes hosts decapods in symbiosis crustaceans, such as Pontonia pinnophylax and Pinnotheres pinnotheres.
Typical epibiosis with organisms that settle on the outer part of the shell such as algae, bryozoans, ascidians and sponges