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Pinna (genus)
Encyclopedia
Pinna is a genus
of pen shells. It is a cosmopolitan genus
of bivalve molluscs characterized by elongated, wedge-shaped shells which most commonly stand point-first in the sea bottom in which they live, anchored by a net of byssus
threads.
Pinna is distinguished from its sibling genus Atrina
by the presence of a sulcus
dividing the nacre
ous region of the valves, and the positioning of the adductor scar on the dorsal
side of shells.
The type species
of the genus is Pinna rudis.
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
.
The genus Pinna is ancient, and is represented in Cretaceous
fossil
s.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of pen shells. It is a cosmopolitan genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of bivalve molluscs characterized by elongated, wedge-shaped shells which most commonly stand point-first in the sea bottom in which they live, anchored by a net of byssus
Byssus
Byssus means both a silky filament by which certain molluscs attach themselves to hard surfaces, and a rare fabric, also called sea silk and its fibre source.-Word:...
threads.
Pinna is distinguished from its sibling genus Atrina
Atrina
Atrina is a cosmopolitan genus of bivalve molluscs characterized by elongated, wedge-shaped shells, distinguished from the genus Pinna by the lack of any grooves in the nacreous lining of the shell, and by the central positioning of the adductor scar....
by the presence of a sulcus
Sulcus (anatomy)
A sulcus is a depression or fissure in the surface of an organ, especially the brain.-Elsewhere:* anterior interventricular sulcus* calcaneal sulcus* coronal sulcus* gingival sulcus* gluteal sulcus* interlabial sulci...
dividing the nacre
Nacre
Nacre , also known as mother of pearl, is an organic-inorganic composite material produced by some mollusks as an inner shell layer; it is also what makes up pearls. It is very strong, resilient, and iridescent....
ous region of the valves, and the positioning of the adductor scar on the dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
side of shells.
The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus is Pinna rudis.
The most completely studied species in the genus is P. nobilis
Pinna nobilis
Pinna nobilis, common name the "noble pen shell" is a species of pen shell, a large marine bivalve mollusc in the family Pinnidae, the 'pen shells'....
, a Mediterranean
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
pen shell which was historically important as the principal source of sea silk
Sea silk
Sea silk is an extremely fine, rare and valuable fabric produced from the long silky filaments or byssus secreted by a gland in the foot of several bivalve molluscs by which they attach themselves to the sea bed....
.
The genus Pinna is ancient, and is represented in Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s.
Species
- Pinna carneaPinna carneaPinna carnea, or the amber pen shell, is a species of bivalve mollusc in the family Pinnidae. It can be found in Caribbean waters, ranging from southern Florida to the West Indies and Bermuda....
Gmelin, 1791 — amber pen shell - Pinna nobilisPinna nobilisPinna nobilis, common name the "noble pen shell" is a species of pen shell, a large marine bivalve mollusc in the family Pinnidae, the 'pen shells'....
Linnaeus, 1758 — noble pen shell - Pinna rudis