''Kuphus polythalamius'' (known as giant ''tamilok'') is a species of

shipworm The shipworms, also called teredo worms or simply teredo (, via Latin ), are marine bivalve molluscs in the family Teredinidae, a group of saltwater clams with long, soft, naked bodies. They are notorious for boring into (and commonly eventual ...

, a marine

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

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Teredinidae.

Description

The tube of ''Kuphus polythalamius'' is known as a crypt and is a calcareous secretion designed to enable the animal to live in its preferred habitat, the mud of

mangrove A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...

swamps. A typical specimen measures in length and is shaped like a truncated elephant's tusk. The wider, anterior end is closed, has a rounded tip, and is about in diameter. From there the tube tapers to an open, posterior end about in diameter, with a central septum. Siphons project through this end for feeding and respiration. They can be withdrawn inside the tube and the end can be sealed with a set of specialised plates or "pallets". The two small

valves A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, ...

of the mollusc are inside the tube along with the mantle, gut and other soft organs. In the intact but otherwise empty tube found on the strandline, they can be seen by X-ray photography.Xray Conchology by Harry G. Lee
Retrieved 2012-01-11.

Longest bivalve

The

giant clam ''Tridacna gigas'', the giant clam, is the best-known species of the giant clam genus ''Tridacna''. Giant clams are the largest living bivalve molluscs. Several other species of "giant clam" in the genus ''Tridacna'' are often misidentified as ...

(''Tridacna gigas'') is generally considered to be the largest bivalve mollusc. It is indeed the heaviest species, growing to over and measuring up to in length,Large Shells
University of Georgia. Retrieved 2012-01-11. but ''Kuphus polythalamius'' holds the record for the largest bivalve by length. A specimen owned by Victor Dan in the United States has a length of , which is considerably longer than the largest giant clam.

Distribution

Today, ''Kuphus polythalamius'' is found in the western Pacific Ocean, the western and eastern Indian Ocean and the Indo-Malaysian area.''Kuphus polythalamia'' (Linnaeus, 1758)
OBIS Indo-Pacific Molluscan Database. Retrieved 2012-01-12. The range includes the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

and

Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

. However, the only thoroughly studied natural habitat of the species is in Kalamansig, Sultan Kudarat in the

.Bayle, Alfred (April 18, 2017)
Rare giant shipworm mollusk found in Philippine waters
Inquirer.net. Retrieved 2020-09-10.

Evolution

Marine biologist Marine biology is the scientific study of the biology of marine life, organisms that inhabit the sea. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology clas ...

Ruth Turner studied shipworms and considered that their common ancestor would have been very like ''Kuphus polythalamius'', the most primitive of the teredinids. She believed that the anatomy of the tube was such that the animal would not have been able to burrow in wood as other modern teredinids do, but would instead have lived buried in soft sediments.

Live specimen

In April 2017, the species became the focus of international attention when the announcement of a scientific study conducted in the

was misinterpreted by foreign news reporters as the discovery of a rare live specimen. The sample was gunmetal black, and very muscular. While other shipworms feed on submerged wood, ''K. polythalamius'' was found to use bacteria in its gills to use hydrogen sulphide in the water as an energy source used to convert carbon dioxide into nutrients. In this respect it resembles the unrelated

giant tube worm ''Riftia pachyptila'', commonly known as the giant tube worm and less commonly known as the giant beardworm, is a marine invertebrate in the phylum Annelida (formerly grouped in phylum Pogonophora and Vestimentifera) related to tube worms ...

, which actually is a worm. Videos uploaded to

YouTube YouTube is an American social media and online video sharing platform owned by Google. YouTube was founded on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim who were three former employees of PayPal. Headquartered in ...

, however, already show Philippine scientists dissecting specimens as far back as 2010, after a news feature on a giant , the local name for the common

, was broadcast on a local TV network. One of several YouTube video captures of a Philippine news report on a giant "tamilok". The upload dates on the videos suggest the news report was broadcast in early 2010 at the latest. The report by local media celebrity Jessica Soho suggests that local residents in the province of

Sultan Kudarat Sultan Kudarat, officially the Province of Sultan Kudarat (; Maguindanao language, Maguindanaon: ''Dairat nu Sultan Kudarat'', Jawi Alphabet, Jawi: دايرت نو سولتان كودرت; ; Ilocano language, Ilocano: ''Probinsia ti Sultan Ku ...

Mindanao Mindanao ( ) is the List of islands of the Philippines, second-largest island in the Philippines, after Luzon, and List of islands by population, seventh-most populous island in the world. Located in the southern region of the archipelago, the ...

island, were familiar enough with the creature to the point of treating it as a delicacy. After the discovery of the species in Sultan Kudarat, various environmental groups launched a campaign to protect the species and its habitat from further destruction and human consumption. Currently, the municipal waters where the species thrive in is protected by the local government.

References

{{Taxonbar, from=Q6445353 polythalamius Chemosynthetic symbiosis Molluscs of the Indian Ocean Molluscs of the Pacific Ocean Bivalves described in 1758 Taxa named by Carl Linnaeus