Pinna nobilis

Appearance

The bivalve shell is usually 30–50 cm (12–20 in) long, but can reach 120 cm (4 ft). Like all pen shells, it is relatively fragile to pollution and shell damage. The inside of the shell is lined with brilliant mother-of-pearl.

The animal secretes these fibres from its byssus gland. They consist of keratin and other proteins and may be as long as 6 cm (2+1⁄2 in). It reaches up to 120 cm (4 ft) of shell length.

Range and habitat

This species is endemic to the Mediterranean Sea, where it lives offshore at depths ranging between 0.5 and 60 m (2 and 200 ft). It could be found buried beneath soft-sediment areas (fine sand, mud, often anoxic).

Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.

In crisis

In 2016, an outbreak of one disease caused the mortality of 99% of its population in Spain. The cause of the disease was a newly discovered pathogen, Haplosporidium pinnae, that still poses a serious threat to the survival of the species. In the past, Pinna nobilis faced extinction, due in part to fishing, incidental killing by trawling and anchoring, and the decline in seagrass fields. Pollution kills eggs, larvae, and adult mussels.

Such threats, even so, have been very localised and have not led to such a widespread and rapid population decline. The pathogen, that is still present in the environment, will make recovery a challenge, so continuing declines are expected.

Pinna nobilis is Critically Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.

Sources

Written for this catalog from the English Wikipedia article on Pinna nobilis, Wikidata item Q536444. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.