Sealife guideThe noble pen shellPinna nobilis
Last updated on 09/02/2025 at 12:22 AM
Taxonomy
- Common name: Noble pen shell, fan mussel
- French name: Grande nacre de Méditerranée, jambonneau de mer, jambonneau hérissé
- Scientific name: Pinna nobilis (Linnée, 1758)
- Family name: Pinnidae
- Order name: Pterioida
- Class name: The bivalves and clams [Bivalvia]
Description
The noble pen shell is a bivalve mollusk that can reach a size of about 3.3 feet. Like all bivalves, it is characterized by a shell composed of two parts, called valves, joined by a hinge. In the case of the noble pen shell, the two valves are symmetrical and shaped like elongated triangles ending in a rounded edge.
The noble pen shell can reach a size of about 3.3 feet
Geographic range
The noble pen shell is a bivalve endemic to the Mediterranean sea. Just like the seagrass meadows of Posidonia where it makes its home, it can be found from shallow waters down to depths of about 165 feet, as long as there is enough light.
Habitat
The noble pen shell lives on sandy bottoms and mainly in
Posidonia seagrass meadows, where it is buried in the sediment up to about one-third of its height or even half in some cases.
Diet
The noble pen shell feeds on living particles (plankton) or dead organic matter suspended in the water, filtering it through its gills. The water current is generated by the movement of tiny cilia.
The noble pen shell is found on sandy bottoms, primarily within Posidonia seagrass meadows
Reproduction
The noble pen shell is hermaphroditic and its reproduction occurs through alternating releases of male and female gametes. Fertilization happens in open water, giving rise to larvae that, after a planktonic stage, settle on a surface or anchor in the sediment to develop and transform into a bivalve.
Did you know ?
At lengths of 3.3 feet or more, the noble pen shell is the largest bivalve mollusk in the Mediterranean ! Alongside the giant clam, it is one of the largest bivalve
mollusks in the world !
If it falls on the seabed, the noble pen shell can right itself using its foot.
The noble pen shell is a protected species: it appears in the decree of November 26, 1992 (published in the Official Journal No. 15 of January 19, 1993), which lists the protected species of marine fauna.
Nevertheless, the noble pen shell is threatened by the decline of Posidonia seagrass meadows and by careless anchoring of boats !
The noble pen shell is listed as many other marine species within The
IUCN Red List of threatened species. The noble pen shell appears in the
IUCN Red List since 2019 within the category Critically Endangered !
Tips for observing
Large adult noble pen shells are easy to spot inside Posidonia meadows, but with attention you can also notice smaller specimens. A golden rule when exploring these meadows: maintain perfect buoyancy and take care with your fin movements to avoid knocking over a noble pen shell !
At lengths of 3.3 feet or more, the noble pen shell is the largest bivalve mollusk in the Mediterranean sea
It is sometimes possible to find small crustaceans such as tiny crabs or shrimp inside the shell of the noble pen shell, where they find both food and shelter without disturbing their host.
Discover also
Chamberlain's sea slug
(Nembrotha chamberlaini)
Flamboyant cuttlefish
(Metasepia pfefferi)
Grapeweed sea slug
(Sacoproteus smaragdinus)
Hooded nudibranch
(Melibe leonina)
Leech sea slug
(Chelidonura hirundinina)
Pustulose wart slug
(Phyllidiella pustulosa)
Stubby squid
(Rossia pacifica)
Tiger cowrie
(Cypraea tigris)
The marine species from Mediterranean sea
Green sea turtle
(Chelonia mydas)
Many-ribbed jellyfish
(Aequorea forskalea)
Mediterranean slipper lobster
(Scyllarides latus)
Purple gorgonian
(Paramuricea clavata)
Red sea-squirt
(Halocynthia papillosa)
Tompot blenny
(Parablennius gattorugine)
Violet sea urchin
(Sphaerechinus granularis)
Yellow sponge Clathrina
(Clathrina clathrus)
Les destinations de plongée
Port Cros island
