The Noble Pen Shell (Maltese: Nakkra tal-Ħarira, Scientific Name: Pinna nobilis) is one of the largest bivalved shellfish in the world. This marine mollusc is endemic to the Mediterranean. Interestingly, a study carried out in a Marine Protected Area to the northwest of Malta has revealed that there is a healthy population of the Noble Pen Shell within this site.
The Noble Pen Shell can reach an impressive 80cm in length or larger. Its brown shell is wedge-shaped and made up of two halves that mirror each other and are joined together by a ‘hinge’. This benthic organism - found in sand or mud close to sea-grass meadows- has one third of its tapering end buried in the sea sediment. Here, the almost stationary shell, is able to find shelter and nourishment.
This large shell is anchored to the ground by a net of silky filaments known as byssus threads. A byssal gland located at the foot of the mollusc secretes a fluid protein which hardens on contact with water, forming these thin and strong filaments. These strands, around 25cm in length, are able to fasten themselves to pebbles, tiny particles, roots and the rhizomes of Posidonia. Interestingly, in the past, byssus threads were made into sea silk, which was woven into valuable garments, such as gloves, shawls and stockings.
Unfortunately, the endangered Noble Pen Shell is vulnerable to damage by anchors and fishing gear, collection, marine pollution and damage to sea-grass meadows.
This mollusc has been protected through the Environment Protection Act, the Bern Convention, the Barcelona Convention and the EU Habitats Directive. MEPA is also helping to safeguard this unique mollusc through the designation of Marine Protection Areas (MPAs).