Pinna Nobilis Or Noble Pen Shell 0 Commentaires
The Pinna Nobilis, commonly known as Noble Pen Shell or Fan Mussel, is one of the largest bivalve molluscs living in muddy bottoms, with the toe of the shell firmly planted in the sand through a lock of long threads, resembling silk, that the animal uses to anchor at the bottom of the sea.
Widespread in the Mediterranean Sea, it lives preferably among Posidonia meadows, from a few meters up to 40 meters deep. It can exceed one meter in height. It is a filtering mollusc that feeds on filtering apparatuses. It is, therefore, a useful indicator of marine pollution. The Pinna hosts a little crab, the Pontonia pinnophylax called Pinna guard, which helps it to catch the little fishes. In fact, when the small fish enter into its valves, kept wide open, the little crab, guarding next to it, gives a signal and the Pinna closes the valves capturing the lunch of which a part will be shared with the Pinna guard. This is one of the lesser-known symbioses of the underwater world (thanks to Nemo, in fact, the symbiotic relationship between clownfish and sea-anemone is far better known) but we have been knowing of the association between the Pinna and the small crustacean from ancient times from the writings of both Aristotle and Pliny.
Today collecting byssus is forbidden but in the past, when Pinna Nobilis lived numerous in our seas, it was detached from the bottom in order to use the tuft of filaments and work it transforming it into byssus, golden fabric object of innumerable myths and legends (read about the Byssus).
As we learn from the philosopher Pliny, as early as the first century after Christ, a tool called pernilegum consisting of two curved iron jaws that, like the dentist's pincer, was used to capture the Pinna and extract it from the bottom of the sea with a rotation of 90°. More roughly, a rope with a knot was used which, like a noose, gripped the base of the Pinna tightly and then was pulled out of the bottom of the sea ... just like a tooth. Then the valves were opened, thus killing the animal, and the tuft was cut from the foot to use the filaments in their full length. By the end of the nineteenth century the textile use of byssus was abandoned, but its therapeutic use, immersed in warm oil, was maintained to cure earache and sometimes even deafness, while fishermen used it as haemostatic if injured during fishing. Edible use is very limited but, being a filtering mollusc, it is extremely risky to eat as it accumulates pollutants and pathogens germs. The Pinna too, like the oyster, often contains a grey or brownish pearl, sometimes gleaming and shiny but of no commercial value.
Unfortunately, there is a great alarm in the Mediterranean that is risking losing its precious symbol, the Pinna Nobilis, decimated by a new species of parasite identified as the killer of large bivalves, the Haplosporidium Pinnae, a microorganism that attacks their digestive gland interfering on their vital process as it weakens the bivalve until it causes its death. Italian marine researchers are working to avoid the extinction process that could be very rapid.
"The risk is not so much local extinction, but of the entire species", says Fernando Rubino, a researcher at CNR IRSA in Taranto. In fact, the effort is to make the species survive because if the species survives, the larvae of the survivors could be disseminated throughout the basin, recolonizing the areas where they have gone extinct. When asked what would happen to the Mediterranean seabed without the big Noble Pen, Rubino said that the negative effects that could derive from its absence, as a "biodiversity enhancer", because it represents the only "hard" substrate in a sandy sea-bottom, and would no longer allow the organisms that normally live on the rock to settle on its shells. Their indicator of marine pollution would also be missing. Moreover, the frequent daily use of faster and more powerful ferryboats is also highly disputed: violent and unnatural movements of the water is unbalancing the congenital verticality of Pinna Nobilis.
Regrettably, today the alarmed divers of the area’s Diving Centers claim that they no longer see a living Pinna Nobilis in our marvellous sea between Golfo Aranci Village and Tavolara Island, but only dead shells lying on the seabed ... the only hope remains to succeed in defeating the killer microorganism and re-colonising the area. The existence of Pinna Nobilis is in the hands of the goodwill of the researchers, to whom all our solidarity goes.
“However, it is quite certain that an almost lock of delicate hair to the touch is born from the animal's belly. This is called by some "Lana from other bisso marino", a distinction from the terrestrial, made of linen, or cotton wool, according to others. It is dark chestnut in colour, and in the greater fins it extends to the length of a palm to the most”. (Buonanni, 1681)
written by Daniela Toti
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