BIOSNIPPET ISSUE 18

Scientific Name: Pinna nobilis

English: Noble pen shell

Maltese: in-nakkra tal-ħarira

The Noble Pen Shell is a large marine bivalve in the family Pinnidae, the pen shells. It is endemic to the Mediterranean and may reach an impressive 120cm in length and live up to 20 years. Its brown shell is wedge-shaped and made up of two halves that mirror each other, joined together by a ‘hinge’. Found in sand or mud close to sea-grass meadows, it has one third of its tapering end buried in sediment, anchoring itself to pebbles and Neptune grass by secreting a net of silky filaments which harden on contact with water. These strands were conventionally made into sea silk and woven into valuable garments.

The Noble Pen Shell prefers clean water with a moderate temperature and good lightning. It feeds on plankton by filtering up to 6 litres of sea water every hour. Being a hermaphrodite, it has both male and female sex organs, releasing sex cells alternatively in the water during the summer months. Occasionally, small crustaceans are found living inside the mussel’s shell. When spotting danger, the resident crustacean nips the mussel, prompting it to close its shell.

The Noble Pen Shell is listed as an endangered species in the Mediterranean Sea. It is vulnerable to damage by anchors, fishing gear, collection, marine pollution and to habitat degradation, hence it is strictly protected through national, international and EU legislation.

Environment and Resources Authority Hexagon House, Spencer Hill Marsa MRS 1441 T: (+356) 2292 3500 E: [email protected] W: era.org.mt