What is Pinna nobilis?

About Pinna nobilis:

• It is a large species of Mediterranean clam, a marine bivalve mollusc in the family Pinnidae.
• The clams, whose shells can grow as much as 1.2 m across, play an important ecological role by filtering sea water and allowing other organisms to flourish.
• It attaches itself to rocks using a strong byssus composed of many silk-like threads which used to be made into cloth.
• The animal secretes these fibres from its byssus gland; they consist of keratin and other proteins and may be as long as 6 cm (2.4 in). The inside of the shell is lined with brilliant mother-of-pearl.
• As with other members of its genus, Pinna nobilis hosts symbiotic shrimp which live inside its shell.
• It is believed that when it sees a threat, the shrimp warns the host, perhaps by retracting its claws or even by pinching. The clam then closes shut.
• It has been demonstrated that the shrimp has a similar filter-feeding diet to its host and the relationship is likely mutualistic.
• Distribution: This species is endemic to the Mediterranean Sea. 
• Threats: It is relatively fragile to pollution and shell damage.
• The clam, known as the noble pen shell or pinna nobilis, started dying out as a deadly pathogen spread in parts of the Mediterranean around 2016.
• Conservation status
  • IUCN: Critically endangered