The Pinnidae are a taxonomic

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of large saltwater clams sometimes known as pen shells. They are marine bivalve molluscs in the order

Pteriida The Pteriida are an order of large and medium-sized marine bivalve mollusks. It includes five families, among them the Pteriidae (pearl oysters and winged oysters). 2010 taxonomy In 2010, a new proposed classification system for the Bivalvia ...

Shell description

The shells of bivalves in this family are fragile and have a long and triangular shape, and in life the pointed end is anchored in sediment using a

byssus A byssus () is a bundle of filaments secreted by many species of bivalve mollusc that function to attach the mollusc to a solid surface. Species from several families of clams have a byssus, including pen shells ( Pinnidae), true mussels (Mytil ...

. The shells have a thin but highly iridescent inner layer of nacre in the part of the shell near the umbos (the pointed end). The family Pinnidae includes the fan shell, '' Atrina fragilis'', and ''

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.Zavodn ...

'', the source of

sea silk Sea silk is an extremely fine, rare, and valuable fabric that is made from the long silky filaments or byssus secreted by a gland in the foot of pen shells (in particular '' Pinna nobilis''). The byssus is used by the clam to attach itself to ...

. Some species are also fished for their food value.

Human use

As RosewaterRosewater, Joseph. (1961). “The Family Pinnidae in the Indo-Pacific.” ''Indo-Pacific Mollusca'', vol. 1, no. 4. September 28, 1961, pp. 175-176. commented in 1961:

"“The Pinnidae have considerable economic importance in many parts of the world. They produce pearls of moderate value. In the Mediterranean area, material made from the holdfast or byssus of ''Pinna nobilis'' Linné has been utilized in the manufacture of clothing for many centuries: gloves, shawls, stockings and cloaks. Apparel made from this material has an attractive golden hue and these items were greatly valued by the ancients. Today, Pinnidae are eaten in Japan, Polynesia, in several other Indo-Pacific island groups, and on the west coast of Mexico. In Polynesia, the valves of ''Atrina vexillum'' are carved to form decorative articles, and entire valves of larger specimens are sometimes used as plates.”

Genera

Genera within the family Pinnidae: * ''

Atrina ''Atrina'' is a cosmopolitan genus of bivalve molluscs belonging to the family Pinnidae. A typical species is '' A. fragilis'', found in British waters. '' A. rigida'' ( Lightfoot, 1786) is found on the southeast coast of North America and in ...

Gray Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed o ...

, 1842 * '' Pinna''

Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...

, 1758 * ''

Streptopinna ''Streptopinna'' is an Indo-Pacific genus of bivalve 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 ...

'' von Martens, 1850 Fine sea silk threads

Shell description

Human use

Genera

References

Further reading