Tridacna squamosina
| Tridacna squamosina | ||||||||||||
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Tridacna squamosina |
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| Scientific name | ||||||||||||
| Tridacna squamosina | ||||||||||||
| Sturany , 1899 |
Tridacna squamosina (syn .: Tridacna costata ) is a shell - type of the subfamily of giant clams (Tridacninae) that the order of Cardiida is provided. The species occurs in very shallow water in the Red Sea and was only rediscovered in 2008.
features
The unevenly hinged case reaches a length of 27 to 32 cm. The lock edge extends to less than half the length of the housing. Five to seven radial, triangular folds extend from the vertebra, creating a zigzag-shaped edge of the housing. The lanceolate byssus opening is comparatively wide. The coat is brown-spotted with wart-like formations on the greenish edge.
differences
Tridacna squamosina differs from Tridacna squamosa by the asymmetrical housing and the smaller adult size (approx. 32 cm against 48 cm). The latter type has four to six radial folds and a smaller byssus opening. It lives with Byssus firmly attached to the subsoil even in somewhat deeper water (up to approx. 25 meters water depth). Tridacna maxima is a little larger (up to 500 mm), lives half-buried and attached with byssus in the sand a little deeper (up to approx. 32 meters water depth).
Geographical distribution
The species has so far only been found in the Red Sea. It lives there in shallow water (less than five meters deep) and is only weakly attached to the ground with a byssus.
Inventory development
Investigations of fossil Tridacna shells have shown that Tridacna costata was the most common type of giant clam in the Red Sea with around 80% of the individuals found around 125,000 years ago. The finds decreased significantly in younger strata; today Tridacna costata accounts for less than one percent of the giant clams found. It is believed that this sharp decline is due to overfishing , which began with the migration of early people from Africa to Asia. Tridacna costata was particularly easy to collect due to its occurrence in very shallow water. Its decline is currently the oldest known case of overfishing. Due to the low population numbers, the species is now considered to be critically endangered.
Taxonomy
The taxon of the species group was described as Tridacna elongata var. Squamosina by Rudolf Sturany as early as 1899 . The name of this variety is available as a species name. The description was almost forgotten. Therefore, the species was described again in 2008 as the new species Tridacna costata by Claudio Richter, Hilly Roa-Quiaoit, Carin Jantzen, Mohammed Al-Zibdah and Marc Kochzius. The latter name is thus a more recent synonym of Tridacna squamosina Sturany, 1899.
supporting documents
- Markus Huber, Anita Eschner: Tridacna (Chametrachea) costata Roa-Quiaoit, Kochzius, Jantzen, Al-Zibdah & Richter from the Red Sea, a junior synonym of Tridacna squamosina Sturany, 1899 (Bivalvia, Tridacnidae). Annals of the Natural History Museum Vienna, B, 112: 153–162, Vienna, 2011 PDF
- Claudio Richter, Hilly Roa-Quiaoit, Carin Jantzen, Mohammed Al-Zibdah and Marc Kochzius: Collapse of a New Living Species of Giant Clam in the Red Sea . In: Current Biology . No. 18, 2008, pp. 1349-1354. doi : 10.1016 / j.cub.2008.07.060 .
- Rudolf Sturany: Expedition SM ship "Pola" in the Red Sea. Northern and southern halves. 1895/96 and 1897/98. Zoological Results XIV Lamellibranchies of the Red Sea. Reports from the Commission for Oceanographic Research. Special print from: Memoranda of the mathematical-natural science class of the Imperial Academy of Sciences, Vienna, 69: 255–295, Vienna 1899 (preprint)
