The most completely studied species in the genus is P. nobilis, a Mediterranean pen shell which was historically important as the principal source of sea silk.
Description
Pinna noblis shell & byssus.Shell.
These pen shells can reach a length of about 80–90 cm (31–35 in). They are characterized by thin, elongated, wedge-shaped, and almost triangular shells with long, toothless edges. The surface of the shells shows radial ribs over their entire length.
Pinna is distinguished from its sibling genus Atrina by the presence of a sulcus dividing the nacreous region of the valves, and the positioning of the adductor scar on the dorsal side of shells.
These bivalves most commonly lie point-first on the sea bottom in which they live, anchored by a net of byssus threads.
Distribution
Species in the genusPinna are geographically widespread. This genus is very ancient, going back up to the Carboniferous period. It is especially represented in Jurassic and Cretaceousfossils.[1]
Frank H.T. Rodes, Herbert S. Zim en Paul R. Shaffer (1993) - Natuurgids Fossielen (het ontstaan, prepareren en rangschikken van fossielen), Zuidnederlandse Uitgeverij N.V., Aartselaar. ISBN D-1993-0001-361
Packard, Earl; Jones, David L. (Sep 1965). "Cretaceous Pelecypods of the Genus Pinna from the West Coast of North America". Journal of Paleontology. 39 (1): 910–915.
"Glossary". Man and Mollusc. Retrieved 2008-01-30.
Coan, E. V.; Valentich-Scott, P. (2012). Bivalve seashells of tropical West America. Marine bivalve mollusks from Baja California to northern Peru. 2 vols, 1258 pp.
Schultz, P. W.; Huber, M. (2013). Revision of the worldwide Recent Pinnidae and some remarks of fossil European Pinnidae. Acta Conchyliorum. 13: 1–164.
