''Pinna rudis'', the rough pen shell or spiny fan-mussel, is a species of
bivalve
Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...
mollusc
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...
in the
family Pinnidae
The Pinnidae are a taxonomic family of large saltwater clams sometimes known as pen shells. They are marine bivalve molluscs in the order Pteriida.
Shell description
The shells of bivalves in this family are fragile and have a long and triang ...
. It is the type species of the genus ''Pinna''. Knowledge about this is sparse, with an absence of specific studies and literature.
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Description
''Pinna rudis'' has a shell that commonly reaches a length of .[ The rough pen shell has a pair of very fragile, long, triangular, wedge–shaped valves, covered with large, protruding scales arranged in quite regular rows. These scales are more prominent close to the opening of the shell. A half-dozen low ribs radiate from the pointed end and run the length of the valves. Said valves are almost symmetrical, toothless, and transparent on the ends. Their color is usually reddish brown.
The spiny fan-mussel lives with the pointed anterior end of its shell vertically anchored to rock or firm sediment by numerous byssus threads. The rear edge of the shell is rounded and free.
''P. rudis'' may be confused with juveniles of '']Pinna nobilis
''Pinna nobilis'', common name the noble pen shell or fan mussel, is a large species of Mediterranean clam, a marine bivalve mollusc in the family Pinnidae, the pen shells. *''Pinna gigas'' Chemnitz
It reaches up to of shell length.Zavodnik, D ...
'', but the former shows a more triangular and robust shell, with fewer and larger protruding scales. Moreover, in ''P. rudis'', the color is more brown or pink-orange, while in juveniles ''P. nobilis'', it is homogeneously yellowish. Lastly, the adults of ''P. nobilis'' easily exceed the size of ''P. rudis'' and totally lose the protuberances on the surface of the shell. Also, the habitats of the two species are different, as ''P. nobilis'' can be found on muddy or sandy bottoms, while ''P. rudis'' prefers rock crevices.[AIAM Italia]
/ref>[DORIS – Données d’Observations pour la Reconnaissance et l’Identification de la faune et de la flore Subaquatiques]
/ref>[ASPIM]
/ref>
Distribution
This species is found in the eastern Atlantic Ocean ( Azores, Saint Helena
Saint Helena () is a British overseas territory located in the South Atlantic Ocean. It is a remote volcanic tropical island west of the coast of south-western Africa, and east of Rio de Janeiro in South America. It is one of three constitu ...
, Morocco), in the Mediterranean (Strait of Gibraltar
The Strait of Gibraltar ( ar, مضيق جبل طارق, Maḍīq Jabal Ṭāriq; es, Estrecho de Gibraltar, Archaic: Pillars of Hercules), also known as the Straits of Gibraltar, is a narrow strait that connects the Atlantic Ocean to the Medi ...
, Almeria, Lipari, Sicily, Tyrrhenian Sea, Ionian Sea
The Ionian Sea ( el, Ιόνιο Πέλαγος, ''Iónio Pélagos'' ; it, Mar Ionio ; al, Deti Jon ) is an elongated bay of the Mediterranean Sea. It is connected to the Adriatic Sea to the north, and is bounded by Southern Italy, including C ...
), in the Black Sea and in the Caribbean waters, ranging from the Gulf of Mexico and southern Florida to the West Indies and Bahamas.[Natura Mediterraneo]
/ref>
Habitat
This species lives in small patches of sand in rocky bottoms and in rock crevices, at depths ranging from the surface to 60 m.[Pacheco, Ricardo J; Barreiros, J. P; Gonçaives, Sílvia C. 2014]
The fan mussel Pinna rudis – occurrence and association with Pontonia pinnophylax in Terceira Island (Azores, NE Atlantic).
/ref>[
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Biology
Like almost all other bivalves, this species is a filter feeder
Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...
. Water is drawn into the shell from above and passed over the ctenidium before being expelled into the open water at the exposed part of the shell. It is a hermaphrodite
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes.
Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...
, the gonads producing both sperm and ova. The larvae are planktonic and drift with the currents.
References
External links
*
{{Taxonbar, from=Q3806056
Pinnidae