''Atrina pectinata'' is a species of

bivalves Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

belonging to 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 ...

. The species is found in the

Old World The "Old World" () is a term for Afro-Eurasia coined by Europeans after 1493, when they became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia in the Eastern Hemisphere, previously ...

. They are important in commercial fishing in Asia. They have the common name of ''kijogae'' 'pen shells'' ''A. pectinata'' is a sedentary long-lived species that lives up to 7 years. The

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 (Mytili ...

has been used in

Sardinia Sardinia ( ; ; ) is the Mediterranean islands#By area, second-largest island in the Mediterranean Sea, after Sicily, and one of the Regions of Italy, twenty regions of Italy. It is located west of the Italian Peninsula, north of Tunisia an ...

to weave

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 mussel to attach itself ...

, as a replacement for the byssus of

critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

'' Pinna nobilis''.

Appearance

''A. pectinata'' are patchy with small clusters. They are commonly called ''kijogae'' 'pen shells''due to their resemblance to a traditional Korean tool. There are two physical morphs of ''A. pectinata'': scaly and smooth, as a result of how the shells develop. Recent research suggests that the two morphs are different enough for them to be taxonomically distinguishable.

Distribution

''A. pectinata'' is widely located in the Indo-West Pacific. The shellfish is an inhabitant of muddy or sandy surfaces. In Korea, the shellfish is located in ocean depths of 20 to 50 m in muddy areas. In the Bohai Sea and Yellow Sea off the coast of China, it is found at habitats ranging from the subtidal zone to depths of 100m. The specific locations of pen shell in Korean waters are the south seashore of Yeojaman, the west seashore of Boryeong and the Taean. In Japan, large numbers of ''A. pectinata'' were traditionally found off the southwestern coast, with commercial activity centered around Kyushu Island.

Development

A suspension study of ''A. pectinata'' showed that in artificial habitats, gonad development occurred at the same time for both male and female pen shells and corresponded to warming water temperatures and increased food availability. ''A. pectinata'' is a broadcast spawner with external fertilization. Spawning occurs after gonad development during the period from May to September and expended gonads are ejected in the fall. Spawning is often triggered by environmental cues such as temperature. 1.6% of spawning individuals are hermaphroditic. ''A. pectinata'' has a pelagic larval phase that lasts about 30 days and mean fecundities of 29 million eggs per year, which suggests high dispersal potential.

Conservation

''A. pectinata'' population has decreased rapidly since 1990 as a result of overfishing, habitat loss from coastal development, pollution, etc. It is a popular food source and is commercially important to a number of countries which makes it a great interest to fisheries. However, an effort to preserve this species has been made by aquaculture development. This species serves as a commercial value, especially in the country of Korea. It serves great purpose in Korean fisheries. The shellfish was also desired for its taste for several years before its decline in the 1990s. ''A. pectinata'' mortality events in 2003 and 2004 reveal that the southwestern Japan population suffered from necrosis in their gills and kidneys not caused by known pathogenic agents. The presence of particles resembling viral matter in the necrotic tissue may hint at an unknown viral agent that can trigger mass mortality events. These mass mortality events are a part of a long decline in the population off the southern coast of Japan. In an effort to conserve the shellfish species,

microsatellite marker A microsatellite is a tract of repetitive DNA in which certain Sequence motif, DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organ ...

s have been used to access the genetic variability and differentiation of ''A. pectinata''. Only one finding has shown that microsatellite markers were able to find genetic differentiation among the wild and hatchery population in Korea. However, more sources need to confirm the genetic information and diversity of the pen shell in order to conserve the species.

References

{{Authority control Pinnidae Taxa named by Carl Linnaeus Bivalves described in 1767 Edible molluscs