Fan Mussel and its hidden Guardian!

Commonly known as Fan Mussel or “Pinna” in Greek (scientific name: “Pinna nobilis”), this is a large shellfish that looks like a big mussel but it has a more impressive and fragile shell that can reach 1 meter in length. This species is endemic to the Mediterranean Sea, and is usually located on sandy seabed in seagrass meadows (in fact “Posidonia oceanica” is rather a plant rather than an alga), down to maximum depth of 60 meters below the surface. It feeds on plankton by filtering the water around it.

Unexpected Surprise

If one is careful enough and approaches the open shell without being perceived, can sometimes spot a small shrimp (3-7 cm) (“Pontonia pinnophylax”) living inside the Pinna. This is a mutually beneficial cohabitation: as long as Pinna offers shelter, the small tenant warns her of possible dangers by stinging and the shell closes hermetically! The role of the small shrimp is also evident in its scientific name “pinnophylax”, which is interpreted as the “Guardian of Pinna”. Sometimes the tenant is not welcome, but a parasitic organism, called the Pea Crab due to his size, and its scientific name is interpreted as “Pinna hunter” (“Pinnotheres pisum”)!

Silk from the Sea

Pinna was a valuable raw material for the textile industry. Traditionally, some coastal populations, mainly in Sicily and Southern Italy, produced a cloth off the muscle fibers that this shell uses to anchor to the bottom substrate. The fabric is known as “marine silk”.

Threats and Protection Status

This humble but special species of our seas is threatened by overfishing, bottom trawling and anchoring that disturb and deplete the benthic habitat, as well as from chemical and biological contamination. Pinna is protected by the “Habitats Directive 92/43/EEC”, which includes this species of EU interest among those that require strict protection. Removing or fishing Pinna is strictly forbidden!

The images come from dives in the waters of the Ionian Sea and more specifically around Kefalonia and Ithaca Islands. They depict species that inhabit and enrich our seas, the very same that host inhabitants and visitors of our islands alike, in the winter or summertime. The hidden wealth of the sea is its own amazing biodiversity. And it is hidden not because it has not been discovered but because it remains unknown to most, so that in general it is considered a vast area empty of any interest, as well as the place for rejecting our waste. The sea is a cradle for life, a nursery for man and a lung for the planet. And in order to protect it we have to know it first.

Tilemachos Beriatos

CMAS 3* diver