Tridacna

Last updated

Tridacna
Temporal range: Miocene – recent [1]
Giant clam (Tridacna gigas) Michaelmas Cay.jpg
Giant clam (T. gigas), Michaelmas Cay, QVD
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Cardiida
Superfamily: Cardioidea
Family: Cardiidae
Subfamily: Tridacninae
Genus: Tridacna
Bruguière, 1797
Synonyms
  • DinodacnaIredale, 1937
  • FlodacnaIredale, 1937 ·
  • PersikimaIredale, 1937
  • SepidacnaIredale, 1937
  • TridachnesRöding, 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
  • TridacneLink, 1807 misspelling (Incorrect subsequent spelling.)
  • VulgodacnaIredale, 1937
Drawing of a Tridacna spp. (NOAA) Giant Clam (Tridacna).jpg
Drawing of a Tridacna spp. ( NOAA )

Tridacna is a genus of large saltwater clams, marine bivalve molluscs in the subfamily Tridacninae, the giant clams. Many Tridacna species are threatened. They have heavy shells, fluted with 4 to 6 folds. The mantle is often brightly coloured. They inhabit shallow waters of coral reefs in warm seas of the Indo-Pacific region. [2] These clams are popular in marine aquaria, and in some areas, such as the Philippines, members of the genus are farmed for the marine aquarium trade. They live in symbiosis with photosynthetic algae (zooxanthellae). Some species are eaten by humans.

Contents

All species in the genus Tridacna are protected under CITES Appendix II. [3]

Etymology

The name Tridacna arises from Greek words tri , meaning three, and dacno, meaning bite. In the Ancient Roman text 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

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

One of the two clam stoups of the Eglise Saint-Sulpice in Paris, carved by Jean-Baptiste Pigalle. Jean-Baptiste Pigalle benitier.jpg
One of the two clam stoups of the Église Saint-Sulpice in Paris, carved by Jean-Baptiste Pigalle.

Tridacna clams are common inhabitants of Indo-Pacific coral reef benthic communities in shallower waters. [10] They live in symbiosis with photosynthetic dinoflagellate algae ( Symbiodinium ) that grow in the mantle tissues. [11] Light penetrates the mantle through small lens-like structures called ocelli. [9] They are sessile in adulthood. By day, the clams spread out their mantle so that the algae receive the sunlight they need to photosynthesize, whereas the colour pigments protect the clam against excessive light and UV radiation. Adult clams can get most (70–100%) of their nutrients from the algae and the rest from filter feeding. [12] 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 pearls with an undulating, porcelain-like surface, [16] which may be described as "non-nacreous pearls".[ citation needed ] The "Pearl of Lao Tzu", also known as the "Pearl of Allah", is the world's largest pearl weighing 6.4 kilogrammes; it was said to have been found inside a 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. 1 2 Huelsken, T., Keyse, J., Liggins, L., Penny, S., Treml, E.A., Riginos, C. (2013) A Novel Widespread Cryptic Species and Phylogeographic Patterns within Several Giant Clam Species (Cardiidae: Tridacna) from the Indo-Pacific Ocean. PLoS ONE, DOI: 10.1371/journal.pone.0080858.
  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. 1 2 Murphy 2002 , p. 25
  10. ↑ Rosewater, J., The Family Tridacnidae in the Indo-Pacific. Indo-Pacific Mollusca, 1:347-408. 1965
  11. ↑ Jantzen, Carin; Wild, Christian; El-Zibdah, Mohammed; Roa-Quiaoit, Hilly Ann; Haacke, Christoph & Richter, Claudio (2008). "Photosynthetic performance of giant clams, Tridacna maxima and T. squamosa, Red Sea". Marine Biology. 155 (2): 211–221. doi:10.1007/s00227-008-1019-7.
  12. ↑ Klumpp, D. W. & Lucas, J. S. (1994). "Nutritional ecology of the giant clams Tridacna tevoroa and T. derasa from Tonga: influence of light on filter-feeding and photosynthesis" (PDF). Marine Ecology Progress Series. 107: 147–156. doi:10.3354/MEPS107147.
  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. ↑ Prager, Ellen (2011), Sex, Drugs, and Sea Slime: The Oceans' Oddest Creatures and Why They Matter , The University of Chicago Press, ISBN   978-0-226-67872-6 (pp. 64–64)
  19. ↑ Markoe, Glenn. Phoenicians. British Museum Press (2000).

Related Research Articles

<i>Pinctada</i> Genus of bivalves

Pinctada is a genus of saltwater oysters, marine bivalve mollusks in the family Pteriidae. These pearl oysters have a strong inner shell layer composed of nacre, also known as "mother of pearl".

<span class="mw-page-title-main">Giant clam</span> Species of bivalve

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

<span class="mw-page-title-main">Strombidae</span> Family of molluscs

Strombidae, commonly known as the true conchs, is a taxonomic family of medium-sized to very large sea snails in the superfamily Stromboidea, and the Epifamily Neostromboidae. The term true conchs, being a common name, does not have an exact meaning. It may generally refer to any of the Strombidae but sometimes is used more specifically to include only Strombus and Lambis. The family currently includes 26 extant, and 10 extinct genera.

<i>Strombus</i> Genus of gastropods

Strombus is a genus of medium to large sea snails, marine gastropod molluscs in the family Strombidae, which comprises the true conchs and their immediate relatives. The genus Strombus was named by Swedish Naturalist Carl Linnaeus in 1758. Around 50 living species were recognized, which vary in size from fairly small to very large. Six species live in the greater Caribbean region, including the queen conch, Strombus gigas, and the West Indian fighting conch, Strombus pugilis. However, since 2006, many species have been assigned to discrete genera. These new genera are, however, not yet found in most textbooks and collector's guides.

<i>Tridacna squamosa</i> Species of bivalve

Tridacna squamosa, known commonly as the fluted giant clam and scaly clam, is a species of bivalve in the family Cardiidae.

<span class="mw-page-title-main">Maxima clam</span> Species of bivalve

The maxima clam, also known as the small giant clam, is a species of bivalve mollusc found throughout the Indo-Pacific region.

<i>Gari</i> (bivalve) Genus of bivalves

Gari is a genus of bivalve molluscs in the family Psammobiidae, known as sunset shells.

<i>Hippopus hippopus</i> Species of mollusc

Hippopus hippopus, also known as the Horse Hoof clam and Strawberry clam, is a species of giant clam in the Subfamily Tridacninae and the genus Hippopus. Hippopus is a delicacy in many Southeast Asian countries due to its high quality meat.

<i>Tridacna crocea</i> Species of bivalve

Tridacna crocea, the boring clam, crocus clam, crocea clam or saffron-coloured clam, is a species of bivalve in the family Cardiidae. It is native to the Indo-Pacific region. It is occasionally found in the aquarium trade where it is often simply referred to as crocea.

<i>Tridacna derasa</i> Species of bivalve

Tridacna derasa, the southern giant clam or smooth giant clam, is a species of extremely large marine clam in the family Cardiidae.

<span class="mw-page-title-main">Tridacninae</span> Subfamily of bivalves

Tridacninae, common name the giant clams, is a taxonomic subfamily of very large saltwater clams, marine bivalve molluscs in the family Cardiidae, the cockles.

<i>Architectonica</i> Genus of gastropods

Architectonica is a genus of sea snails in the family Architectonicidae.

<i>Pupa</i> (gastropod) Genus of gastropods

Pupa is a genus of small sea snails, marine gastropod molluscs in the family Acteonidae.

<i>Coralliophila</i> Genus of gastropods

Coralliophila is a genus of sea snails, marine gastropod mollusks in the subfamily Coralliophilinae, the coral snails, within the family Muricidae, the murex snails and rock snails.

<i>Drupa</i> (gastropod) Genus of gastropods

Drupa is a genus of sea snails, marine gastropod mollusks in the family Muricidae, the murex snails or rock snails. It occurs in the Indo-Pacific.

<i>Tridacna noae</i> Species of bivalve

Tridacna noae, also known as Noah’s giant clam or the Teardrop giant clam, is a species of giant clam. Up until recently, T. noae was confused with the small giant clam Tridacna maxima, but is now known to be its own independent species. It has a broad distribution in the Indo-Pacific.

<i>Gafrarium pectinatum</i> Species of mollusc

Gafrarium pectinatum, also known as Gafrarium tumidum, is a species of the genus Gafrarium in the family of Veneridae, order Veneroida in the bivalve class. They are edible clams. WoRMS believe the latter is the synonyms of the other one, but malocologist from Taiwan distinguish the two from the patterns of their shells

<i>Tridacna squamosina</i> Species of bivalve

Tridacna squamosina is a species of the Tridacna genus, the giant clams. These animals are bivalve mollusks belonging to the family Cardiidae identified by Sturany 1899.

References

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.