''Limaria fragilis'', the fragile file clam, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of bivalve mollusc in the

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 ...

Limidae. It is found in shallow waters in the Indian and Pacific Oceans and has the ability to swim.

Description

The fragile file clam has a pair of hinged, thin, asymmetric white valves and a red mantle with a fringe of long tapering pink and grey banded tentacles at its edge. Also around the margin of the mantle are a row of tiny eyespots that can detect light and shade, and may alert the animal to the approach of a predator.''Limaria fragilis''
Saltcorner. Retrieved 2012-04-20.

Distribution and habitat

The fragile file clam is widely distributed in the Indo-Pacific region. Its range includes the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

, the

Marshall Islands The Marshall Islands ( mh, Ṃajeḷ), officially the Republic of the Marshall Islands ( mh, Aolepān Aorōkin Ṃajeḷ),'' () is an independent island country and microstate near the Equator in the Pacific Ocean, slightly west of the Intern ...

, the

Cook Islands ) , image_map = Cook Islands on the globe (small islands magnified) (Polynesia centered).svg , capital = Avarua , coordinates = , largest_city = Avarua , official_languages = , lan ...

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

, the Chagos Archipelago,

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

and the

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; ...

. It often conceals itself in crevices or under stones with just its tentacles protruding.

Biology

The fragile file clam is a protandrous hermaphrodite. Juveniles start life as males and change sex to females as they grow. Fragile file clams have the ability to emit flashes of biolumiscent light, though why they do this is unclear. The fragile file clam can swim slowly and continuously for about 5 minutes at a time. It does this by opening and closing its valves and expelling water in a stream from either side of the hinge, a form of

jet propulsion Jet propulsion is the propulsion of an object in one direction, produced by ejecting a jet of fluid in the opposite direction. By Newton's third law, the moving body is propelled in the opposite direction to the jet. Reaction engines operatin ...

. In an aquarium, the animal flits around knocking into other objects. It uses its mantle tentacles in an oar-like fashion when swimming. Sometimes it sheds the longest tentacles and can still swim effectively without them, increasing the frequency of valve clapping to maintain speed. The detached tentacles secrete a noxious substance and continue to writhe after they are severed which may distract aggressors. It was originally thought that the energy for swimming was supplied aerobically through respiration with little input from anaerobic glycolysis and arginine phosphate. Further study showed that this was not the case. There was a high level of arginine kinase and certain other

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

s in the adductor muscles which was indicative of the conversion of arginine phosphate for energy production. Up to 23% of the ATP used for energy transfer was supplied in this way while the animal was swimming.

References

External links

* {{Taxonbar, from=Q6548889 Limidae Bivalves described in 1791 Taxa named by Johann Friedrich Gmelin