EUROPA - UNDERWATER FAUNA AND FLORA: Noble pen shell

EUROPA – UNDERWATER FAUNA AND FLORA

Noble pen shell (Pinna nobilis)

The noble pen shell (Pinna nobilis) is a Mediterranean endemic species and the largest bivalve mollusc in the Mediterranean Sea. Its shell rate growth is among the fastest of any species and its shell can reach a length of more than a metre. It is generally found in sedimentary seabed habitats, most frequently in areas of seagrass, since the survival rate of fragile young shells is highest when they are hidden among grasses. Pinna nobilis plays a key ecological role by filtering water and retaining organic matter, which contributes to water clarity. By offering a habitat to numerous organisms, it also increases biodiversity. It is also important in human culture, since it is a source of sea silk and pearls and its shell is used as a receptacle. Its flesh is also prized.

The noble pen shell population began to recover significantly after 2000 when the species was listed as endangered and granted protected status. In 2016 mass mortality events were recorded in the western Mediterranean, mainly caused by the parasite Haplosporidium pinnae, which in 2020 also arrived in the Gulf of Trieste. Today the noble pen shell is listed among critically endangered species.

Borut Mavrič, Marine Biology Station, National Institute of Biology