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The giant clams are the members of the
clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two shel ...
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
'' Tridacna'' that are the largest
living Living or The Living may refer to: Common meanings *Life, a condition that distinguishes organisms from inorganic objects and dead organisms ** Living species, one that is not extinct *Personal life, the course of an individual human's life * H ...
bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of marine and freshwater Mollusca, molluscs that have laterally compressed bodies enclosed by a shell consisting of two hing ...
mollusk 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 e ...
s. There are actually several species of "giant clams" in the genus '' Tridacna'', which are often misidentified for ''Tridacna gigas'', the most commonly intended species referred to as "the giant clam". ''Tridacna gigas'' is one of the most endangered clam species.
Antonio Pigafetta Antonio Pigafetta (; – c. 1531) was an Venetian scholar and explorer. He joined the expedition to the Spice Islands led by explorer Ferdinand Magellan under the flag of the emperor Charles V and after Magellan's death in the Philippine Islands, ...
documented these in his journal as early as 1521. One of a number of large clam species native to the shallow
coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of Colony (biology), colonies of coral polyp (zoology), polyps held together by calcium carbonate. Most coral reefs are built from stony corals, wh ...
s of the South
Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...
and
Indian Indian or Indians may refer to: Peoples South Asia * Indian people, people of Indian nationality, or people who have an Indian ancestor ** Non-resident Indian, a citizen of India who has temporarily emigrated to another country * South Asia ...
oceans, they can weigh more than , measure as much as across and have an average lifespan in the wild of over 100 years. They are also found off the shores of 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 ...
and in the
South China Sea The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by the shores of South China (hence the name), in the west by the Indochinese Peninsula, in the east by the islands of Taiwan and northwestern Ph ...
in the coral reefs of
Sabah Sabah () is a state of Malaysia located in northern Borneo, in the region of East Malaysia. Sabah borders the Malaysian state of Sarawak to the southwest and the North Kalimantan province of Indonesia to the south. The Federal Territory ...
(
Malaysian Borneo East Malaysia (), or the Borneo States, also known as Malaysian Borneo, is the part of Malaysia on and near the island of Borneo, the world's third-largest island. Near the coast of Sabah is a small archipelago called Labuan. East Malaysia li ...
). The giant clam lives in flat
coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...
sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class ...
or broken coral and can be found at depths of as much as 20 m (66 ft).
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, p. 10.
Its range covers the
Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...
, but populations are diminishing quickly, and the giant clam has become extinct in many areas where it was once common. The
maxima clam The maxima clam (''Tridacna maxima''), also known as the small giant clam, is a species of bivalve mollusc found throughout the Indo-Pacific region.MolluscaBase eds. (2022). MolluscaBase. Tridacna maxima (Röding, 1798). Accessed through: World R ...
has the largest geographical distribution among giant clam species; it can be found off high- or low-elevation islands, in
lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into '' coastal lagoons'' (or ''barrier lagoons ...
s or
fringing reef A fringing reef is one of the three main types of coral reef. It is distinguished from the other main types, barrier reefs and atolls, in that it has either an entirely shallow backreef zone (lagoon) or none at all. If a fringing reef grows dire ...
s. Its rapid growth rate is likely due to its ability to cultivate
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...
in its body tissue. Although
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...
l clams are
plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...
ic, they become sessile in adulthood. The creature's
mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...
tissues act as a
habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
for the
symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or para ...
single-celled
dinoflagellate The dinoflagellates ( Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...
algae (
zooxanthellae Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus ''S ...
) from which the adult clams get most of their nutrition. By day, the clam opens its shell and extends its mantle tissue so that the algae receive the sunlight they need to
photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...
e.


Anatomy

Young ''T. gigas'' are difficult to distinguish from other species of
Tridacninae Tridacninae, common name, the giant clams, is a taxonomic subfamily of very large saltwater clams, marine bivalve molluscs in the family Cardiidae, the cockles. Description This subfamily contains the largest living bivalve species, including ' ...
. Adult ''T. gigas'' are the only giant clams unable to close their shells completely. Even when closed, part of the mantle is visible, unlike the very similar '' T. derasa''. However, this can only be recognized with increasing age and growth. Small gaps always remain between shells through which retracted brownish-yellow mantle can be seen.
Knop KNOP-TV (channel 2) is a television station in North Platte, Nebraska, United States, affiliated with NBC. It is owned by Gray Television alongside two low-power stations: CBS affiliate KNPL-LD (channel 10) and Class A Fox affiliate KIIT-CD ( ...
, p. 32.
''Tridacna gigas'' has four or five vertical folds in its shell; this is the main characteristic that separates it from the similar shell of ''T. derasa'', which has six or seven vertical folds. As with massive deposition of coral matrices composed of calcium carbonate, the
bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of marine and freshwater Mollusca, molluscs that have laterally compressed bodies enclosed by a shell consisting of two hing ...
s containing
zooxanthellae Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus ''S ...
have a tendency to grow massive calcium carbonate shells. The mantle's edges are packed with
symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or para ...
zooxanthellae that presumably utilize
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...
,
phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...
s, and
nitrate Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insolu ...
s supplied by the clam. The mantle border itself is covered in several hundred eyespots about .5mm in diameter. Each one consists of a small cavity containing a pupil-like aperture and a base of one hundred or more photoreceptors. These receptors allow ''T. gigas'' to respond to sudden dimming of light by withdrawing their mantles and partially closing their shells, presumably to protect from potential predators. They do not retract their mantles in response to increased illumination, but it has been observed that a change in the direction of light results in a shift in mantle orientation. In addition to a dimming response, ''T. gigas'' also responds to the movement of an object before a shadow has been cast. In order for this to happen, an image forming optical system is required as the response is based on the local dimming of one part of the generated image relative to the rest. This sequential dimming of receptors caused by the movement of a dark object allows enough time for the mantle to be retracted before a potential predator is directly overhead and casting a shadow.


Largest specimens

The largest known ''T. gigas'' specimen measured . It was discovered around 1817 on the north western coast of
Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
,
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...
, and its shells are now on display in a museum in
Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label=Ulster Scots dialect, Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is #Descriptions, variously described as ...
. The joint weight of the two shells is , which suggests that the live weight of the animal would have been roughly .
Knop KNOP-TV (channel 2) is a television station in North Platte, Nebraska, United States, affiliated with NBC. It is owned by Gray Television alongside two low-power stations: CBS affiliate KNPL-LD (channel 10) and Class A Fox affiliate KIIT-CD ( ...
, p. 31.
Another unusually large giant clam was found in 1956 off the Japanese island of Ishigaki. However, it was not examined scientifically before 1984. The shell's length was and the weight of the shells and soft parts was . Scientists estimated the live weight to be around . File:Tridacna maxima Voavah.JPG, Huge
maxima clam The maxima clam (''Tridacna maxima''), also known as the small giant clam, is a species of bivalve mollusc found throughout the Indo-Pacific region.MolluscaBase eds. (2022). MolluscaBase. Tridacna maxima (Röding, 1798). Accessed through: World R ...
specimen in
Baa Atoll Baa Atoll (includes Southern Maalhosmadulu Atoll or Maalhosmadulu Dhekunuburi, Fasdhūtherē Atoll, and Goifulhafehendhu Atoll) is an administrative division of the Maldives. It consists of three separate natural atolls, namely southern Maalhosmad ...
,
Maldives Maldives (, ; dv, ދިވެހިރާއްޖެ, translit=Dhivehi Raajje, ), officially the Republic of Maldives ( dv, ދިވެހިރާއްޖޭގެ ޖުމްހޫރިއްޔާ, translit=Dhivehi Raajjeyge Jumhooriyyaa, label=none, ), is an archipelag ...
File:Giant Clam (Tridacna gigas) (6058446919).jpg, Giant clam in
Bunaken Bunaken is an island of 8 km2, part of the Bunaken National Marine Park. Bunaken is located at the northern tip of the island of Sulawesi, Indonesia. It belongs administratively to the municipality of Manado. Scuba diving attracts many v ...
island,
Sulawesi Sulawesi (), also known as Celebes (), is an island in Indonesia. One of the four Greater Sunda Islands, and the world's eleventh-largest island, it is situated east of Borneo, west of the Maluku Islands, and south of Mindanao and the Sulu ...
,
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...
File:Tridacna gigas 01 by Line1.JPG, Empty giant clam shell in the French
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File:Tridacna gigas.001 - Aquarium Finisterrae.JPG, Empty shell from the
Aquarium Finisterrae Aquarium Finisterrae (Aquarium of the end of the World) is an aquarium located in A Coruña, Galicia, Spain. It is an interactive centre of the sciences of marine biology, oceanography. It advocates wildlife preservation, particularly the sea ec ...
in Spain File:Living giant clam (Tridacna gigas), Waikiki Aquarium.JPG, Giant clam in
Waikiki Aquarium Waikiki (; haw, Waikīkī; ; also known as Waikiki Beach) is a neighborhood of Honolulu on the south shore of the island of Oahu in the U.S. state of Hawaii. Waikiki is most famous for Waikiki Beach, which is one of six beaches in the district ...
,
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,
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
, United States


Ecology


Feeding

While giant clams filter-feed, symbiotic algae provide them with an essential supplementary source of nutrition. These plants consist of unicellular algae, whose
metabolic Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
products add to the clam's filter food. This enables giant clams to grow as large as one meter in length even in nutrient-poor coral-reef waters. The clams cultivate algae in a special
circulatory system The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
which enables them to keep a substantially higher number of symbionts per unit of volume. In very small clams— dry tissue weight—filter feeding provides about 65% of total carbon needed for
respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellul ...
and growth; larger clams (10 g) acquire only 34% of carbon from this source. A single species of zooxenthellae may be symbionts of both giant clams and nearby reef–building ( hermatypic) corals.


Reproduction

''Tridacna gigas'' reproduce sexually and are
hermaphrodites 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 taxonomic groups of animals (mostly invertebrates) do not have sep ...
(producing both eggs and
sperm Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, ...
). Self-fertilization is not possible, but this characteristic does allow them to reproduce with any other member of the species. This reduces the burden of finding a compatible mate, while simultaneously doubling the number of offspring produced by the process. As with all other forms of sexual reproduction, hermaphroditism ensures that new gene combinations be passed to further generations. Since giant clams cannot move themselves, they adopt broadcast spawning, releasing sperm and eggs into the water. A transmitter substance called ''spawning induced substance'' (SIS) helps synchronize the release of sperm and eggs to ensure fertilization. The substance is released through a syphonal outlet. Other clams can detect SIS immediately. Incoming water passes
chemoreceptors A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance (endogenous or induced) to generate a biological signal. This signal may be in the form of an action potential, if the chemorecept ...
situated close to the incurrent syphon, which transmit the information directly to the cerebral
ganglia A ganglion is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system there are both sympathe ...
, a simple form of brain. Detection of SIS stimulates the giant clam to swell its mantle in the central region and to contract its adductor muscle. Each clam then fills its water chambers and closes the incurrent syphon. The shell contracts vigorously with the adductor's help, so the excurrent chamber's contents flows through the excurrent syphon. After a few contractions containing only water, eggs and sperm appear in the excurrent chamber and then pass through the excurrent syphon into the water. Female eggs have a diameter of . Egg release initiates the reproductive process. An adult ''T. gigas'' can release more than 500 million eggs at a time. Spawning seems to coincide with incoming tides near the second (full), third, and fourth (new) quarters of the moon phase. Spawning contractions occur every two or three minutes, with intense spawning ranging from thirty minutes to two and a half hours. Clams that do not respond to the spawning of neighboring clams may be reproductively inactive.


Development

The fertilized egg floats in the sea for about 12 hours until eventually a
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...
(trocophore) hatches. It then starts to produce a calcium carbonate shell. Two days after fertilization it measures . Soon it develops a "foot," which is used to move on the ground; it can also swim to search for appropriate habitat. At roughly one week of age, the clam settles on the ground, although it changes location frequently within the first few weeks. The larva does not yet have symbiotic algae, so it depends completely on
plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...
. Free floating zooxanthellae are also captured while filtering food. Eventually the front adductor muscle disappears and the rear muscle moves into the clam's center. Many small clams die at this stage. The clam is considered a juvenile when it reaches a length of . It is difficult to observe the growth rate of ''T. gigas'' in the wild, but laboratory-reared giant clams have been observed to grow a year.


Human relevance

The main reason that giant clams are becoming endangered is likely to be intensive exploitation by bivalve fishing vessels. Mainly large adults are killed, since they are the most profitable. The giant clam is considered a delicacy in Japan (known as ''himejako''), France,
Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainland ...
and many Pacific Islands. Some Asian foods include the meat from the muscles of clams. On the
black market A black market, underground economy, or shadow economy is a clandestine market or series of transactions that has some aspect of illegality or is characterized by noncompliance with an institutional set of rules. If the rule defines the ...
, giant clam shells are sold as decorative accoutrements. At times large amounts of money were paid for the adductor muscle, which Chinese people believed have
aphrodisiac An aphrodisiac is a substance that increases sexual desire, sexual attraction, sexual pleasure, or sexual behavior. Substances range from a variety of plants, spices, foods, and synthetic chemicals. Natural aphrodisiacs like cannabis or cocai ...
powers.


Legend

As is often the case with uncharacteristically large species, the giant clam has been historically misunderstood. It was known in times past as the "killer clam" and "man-eating clam", and reputable scientific and technical manuals once claimed that the great mollusc had caused deaths; versions of the ''
U.S. Navy Diving Manual The ''U.S. Navy Diving Manual'' is a book used by the US Navy for diver training and diving operations. Overview The US Navy first provided a diving manual for training and operational guidance in 1905, and the first book titled ''Diving Manu ...
'' even gave detailed instructions for releasing oneself from its grasp by severing the adductor muscles used to close its shell. In an account of the discovery of the Pearl of Lao Tzu, Wilburn Cobb said he was told that a Dyak diver was drowned when the ''Tridacna'' closed its shell on his arm. Today the giant clam is considered neither aggressive nor particularly dangerous. While it is certainly capable of gripping a person, the shell's closing action is defensive, not aggressive, and the shell valves close too slowly to pose a serious threat. Furthermore, many large individuals are unable to completely close their shells.


Aquaculture

Mass culture of giant clams began at the Micronesian Mariculture Demonstration Center in
Palau Palau,, officially the Republic of Palau and historically ''Belau'', ''Palaos'' or ''Pelew'', is an island country and microstate in the western Pacific. The nation has approximately 340 islands and connects the western chain of the ...
(Belau). A large
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
n government-funded project from 1985 to 1992 mass-cultured giant clams, particularly ''T. gigas'' at
James Cook University James Cook University (JCU) is a public university in North Queensland, Australia. The second oldest university in Queensland, JCU is a teaching and research institution. The university's main campuses are located in the tropical cities of Cairn ...
's Orpheus Island Research Station, and supported the development of hatcheries in the Pacific Islands and the Philippines.Fitt W.K (Ed.) 1993. Biology and Mariculture of Giant Clams; a workshop held in conjunction with the 7th International Coral Reef Symposium, 21–26 June 1992, Guam, USA Recent developments in
aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...
, specifically at
Harbor Branch Oceanographic Institute Harbor Branch Oceanographic Institute (HBOI, FAU Harbor Branch) is a non-profit oceanographic institution operated by Florida Atlantic University in Fort Pierce, Florida, United States. Founded in 1971 as non-profit research organization, the i ...
in
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, and in 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 Inte ...
, have succeeded in tank-raising ''T. gigas'', both for use in home
aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...
s and for release into the wild. Seven of the ten known species of giant clams in the world are found in the coral reefs of the South China Sea. A programme to propagate endangered giant clams for release into the wild has been ongoing since 2007. Undertaken by the Marine Ecology Research Centre (www.merc-gayana.com) based in Gaya Island just west of Sabah's capital, Kota Kinabalu, the programme successfully nurtured all seven species of the giant clams found in Malaysian waters to sufficient maturity for them to be placed in an ocean nursery for the first time during an awareness month from 22 March until 22 April 2012 in Maloham Bay. This marine awareness month had been planned to highlight and celebrate MERC's success in raising the giant clam larvae (called "spats") to juvenile stage, to highlight the importance of the giant clams and to raise awareness and support with the general public on the threats that are faced by the giant clams within the sea. During this marine awareness month, the coral restoration programme entered its final stage and attachment of 1000 one-year-old coral fragments grown at MERC's ocean nursery onto the coral reef were done throughout the month. The coral restoration programme is aimed to provide the giant clams with a suitable home surroundings when they are big enough in the future to be placed onto the reef.


Conservation status

There is concern among
conservationists The conservation movement, also known as nature conservation, is a political, environmental, and social movement that seeks to manage and protect natural resources, including animal, fungus, and plant species as well as their habitat for the ...
about whether those who use the species as a source of livelihood are overexploiting it. The numbers in the wild have been greatly reduced by extensive harvesting for food and the aquarium trade. The species is listed in Appendix II of the
Convention on International Trade in Endangered Species CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of intern ...
(CITES) meaning international trade (including in parts and derivatives) is regulated.


Gallery

File:Tridacna giant clam.jpg, Green and blue giant clam from
East Timor East Timor (), also known as Timor-Leste (), officially the Democratic Republic of Timor-Leste, is an island country in Southeast Asia. It comprises the eastern half of the island of Timor, the exclave of Oecusse on the island's north-w ...
File:Giant clam with diver.jpg, Largest of all clam species File:Tridacna gigas.jpg, A giant clam from East Timor of over one meter in length.


See also

*''
Platyceramus ''Platyceramus'' was a genus of Cretaceous bivalve molluscs belonging to the extinct inoceramid lineage. It is sometimes classified as a subgenus of ''Inoceramus''. Size The largest and best known species is ''P. platinus''. Individuals of th ...
'', the largest bivalve in the fossil record


References


Cited sources

*


Further reading

*Schwartzmann C, G Durrieu, M Sow, P Ciret, CE. Lazareth and J-C Massabuau. (2011) ''In situ'' giant clam growth rate behavior in relation to temperature: a one-year coupled study of high-frequency non-invasive valvometry and sclerochronology
Limnol. Oceanogr. 56(5)
1940–1951 (Open access) *


External links

* ARKive �
images and movies of the giant clam ''(Tridacna gigas)''
* ''Tridacna gigas'' entry o



at Universiti Sains Malaysia
Giant Clams of the Great Barrier ReefMicrodocs





MolluSCAN eye project
, a website dedicated to the ''in situ'' study of bivalve mollusks around the world * {{Taxonbar, from=Q751784 Bivalves described in 1758 Taxa named by Carl Linnaeus Tridacna