Tridacna

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Tridacna
Temporal range: Miocene – recent[1]
Giant clam (T. gigas), Michaelmas Cay, QVD
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Cardiida
Superfamily: Cardioidea
Family: Cardiidae
Subfamily: Tridacninae
Genus: Tridacna
Bruguière, 1797
Synonyms
  • Dinodacna Iredale, 1937
  • Flodacna Iredale, 1937 ·
  • Persikima Iredale, 1937
  • Sepidacna Iredale, 1937
  • Tridachnes Röding, 1798 ·
  • Tridacna (Chametrachea) Mörch, 1853 · alternate representation
  • Tridacna (Chametrachea) Herrmannsen, 1846 (Not used as a valid name (ICZN Art. 11.5.2))
  • Tridacna (Persikima) Iredale, 1937 · alternate representation
  • Tridacna (Tridacna) Bruguière, 1797 · alternate representation
  • Tridacne Link, 1807 misspelling (Incorrect subsequent spelling.)
  • Vulgodacna Iredale, 1937
NOAA
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Tridacna is a

zooxanthellae
). Some species are eaten by humans.

All species in the genus Tridacna are protected under

CITES Appendix II.[3]

Etymology

The name Tridacna arises from Greek words

Natural History, Pliny the Elder explained the nomenclature comes from the fact that "they are so large as to require three bites in eating them.”[4]

List of Species, Systematics, and Phylogeny

The genus contains the following species:[5][6]

Synonyms
  • Tridacna acuticostata G. B. Sowerby III, 1912: synonym of Tridacna maxima (Röding, 1798)
  • Tridacna compressa Reeve, 1862: synonym of Tridacna (Chametrachea) maxima (Röding, 1798) represented as Tridacna maxima (Röding, 1798) (junior subjective synonym)
  • Tridacna costata Roa-Quiaoit, Kochzius, Jantzen, Zibdah & Richter, 2008: synonym of Tridacna squamosina Sturany, 1899
  • Tridacna cumingii Reeve, 1862: synonym of Tridacna (Chametrachea) crocea Lamarck, 1819 represented as Tridacna crocea Lamarck, 1819 (junior subjective synonym)
  • Tridacna detruncata Bianconi, 1869: synonym of Tridacna maxima (Röding, 1798) (junior subjective synonym)
  • Tridacna elongata Lamarck, 1819: synonym of Tridacna maxima (Röding, 1798) (junior subjective synonym)
  • Tridacna ferruginea Reeve, 1862: synonym of Tridacna (Chametrachea) crocea Lamarck, 1819 represented as Tridacna crocea Lamarck, 1819 (junior subjective synonym)
  • Tridacna fossor Hedley, 1921: synonym of Tridacna maxima (Röding, 1798)
  • Tridacna glabra Link, 1807: synonym of Tridacna derasa (Röding, 1798) (junior subjective synonym, synonym)
  • Tridacna imbricata (Röding, 1798): synonym of Tridacna (Chametrachea) maxima (Röding, 1798) represented as Tridacna maxima (Röding, 1798)
  • Tridacna lamarcki Hidalgo, 1903: synonym of Tridacna squamosa Lamarck, 1819 (synonym - pars)
  • Tridacna lanceolata G. B. Sowerby II, 1884: synonym of Tridacna (Chametrachea) maxima (Röding, 1798) represented as Tridacna maxima (Röding, 1798) (unaccepted > junior subjective synonym)
  • Tridacna lorenzi Monsecour, 2016 -- Mascarene region: synonym of Tridacna lorenzi K. Monsecour, 2016: synonym of Tridacna (Chametrachea) rosewateri Sirenko & Scarlato, 1991 represented as Tridacna rosewateri Sirenko & Scarlato, 1991
  • Tridacna mutica Lamarck, 1819: synonym of Tridacna (Chametrachea) maxima (Röding, 1798) represented as Tridacna maxima (Röding, 1798) (synonym - pars)
  • Tridacna ningaloo Penny & Willan, 2014: synonym of Tridacna noae (Röding, 1798)
  • Tridacna obesa G. B. Sowerby III, 1899: synonym of Tridachnes derasa Röding, 1798: synonym of Tridacna derasa (Röding, 1798) (junior subjective synonym)
  • Tridacna reevei Hidalgo, 1903: synonym of Tridacna (Chametrachea) maxima (Röding, 1798) represented as Tridacna maxima (Röding, 1798) (junior subjective synonym, synonym)
  • Tridacna rudis Reeve, 1862: synonym of Tridacna (Chametrachea) maxima (Röding, 1798) represented as Tridacna maxima (Röding, 1798) (junior subjective synonym)
  • Tridacna serrifera Lamarck, 1819: synonym of Tridacna derasa (Röding, 1798)
  • Tridacna tevoroa Lucas, Ledua & Braley, 1990: synonym of Tridacna mbalavuana Ladd, 1934
  • Tridacna troughtoni Iredale, 1927: synonym of Tridacna maxima (Röding, 1798) (junior subjective synonym)

An alternative older classification recognises a third subgenus Persikima containing T. derasa and T. mbalavuana.[7] Recent biochemical studies have suggested that there may exist morphologically indistinct

cryptic species.[2][8]

Anatomy

Compared to other clams, the soft mantle that secretes the shell is greatly expanded. The clams even have small lens-like structures called

ocelli through which light penetrates.[9]

Ecology and behaviour

.

Tridacna clams are common inhabitants of

When disturbed, the clam closes its shell. The popular opinion that they pose danger to divers who get trapped or injured between the closing sharp-edged shell is not very real, as the closing reaction is quite slow. Their large size and easy accessibility has caused overfishing and collapse of the natural stocks in many places and extirpation in some of the species.[13] They are being sustainably farmed in some areas,[14] both for the seafood market in some Asian countries and for the aquarium trade.[15]

Tridacna clams can produce large white

Tridacna gigas by a Filipino diver in 1934.[17][18]

Artistic use

Over a hundred examples of carved Tridacna shells have been found in archaeological expeditions from Italy to the Near East. Similar in artistic style, they were probably produced in the mid-seventh century, made or distributed from the southern coast of Phoenicia. The backs and interior perimeters of the shells show animal, human, and floral motifs, while the interiors typically show recumbent sphinxes. The umbo of the shell is in the shape of a human female or bird's head. They were probably used to store eye cosmetics.[19]

Images

Notes

  1. ^ "The Paleobiology Database". Paleodb.org. Retrieved 2012-05-20.
  2. ^ .
  3. ^ "Checklist of CITES species".
  4. ^ Barnett, Cynthia (2021-07-06). "The History, Myth, and Future of the Giant Clam". Atlas Obscura. Retrieved 2023-11-18.
  5. ^ WoRMS. (2009). Tridacna. Accessed through the World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=205753 on 2009-01-08.
  6. ^ Schneider, J.A.,and O´Foighil, D. Phylogeny of Giant Clams (Cardiidae: Tridacninae) Based on Partial Mitochondrial 16S rDNA Gene Sequences. Molecular Phylogenetics and Evolution Vol. 13, No. 1, October, pp. 59–66, 1999
  7. ^ Benzie,J.A.H. and Williams,S.T. Phylogenetic relationships among giant clam species (Mollusca: Tridacnidae) determined by protein electrophoresis. Marine Biology (1998) 132: 123±133
  8. ^ Mohamed, N.M. et al., Molecular Genetic Analyses of Giant Clam (Tridacna sp.) Populations in the Northern Red Sea. Asian Journal of Biochemistry, 1 (4): 338-342 (2006)
  9. ^ a b Murphy 2002, p. 25
  10. ^ Rosewater, J., The Family Tridacnidae in the Indo-Pacific. Indo-Pacific Mollusca, 1:347-408. 1965
  11. .
  12. .
  13. ^ J.W. Copland and J.S. Lucas, (Eds.), Giant Clams in Asia and the Pacific Vol. 9, Australian Center for International Agricultural Research, Canberra(1988).
  14. ^ Murphy 2002, p. 28
  15. ^ "Aquarium Invertebrates: A Trip to an Indonesian Coral and Clam Farm". advancedaquarist.com.
  16. ^ CIBJO (2007) THE PEARL BOOK:: Natural, Cultured & Imitation Pearls: Terminology & Classification – 5.216. Tridacna gigas (p. 28)
  17. ^ Natural History – PICKS FROM THE PAST: NOVEMBER 1939 – The Pearl of Allah
  18. (pp. 64–64)
  19. ^ Markoe, Glenn. Phoenicians. British Museum Press (2000).

References