Glyphis siamensis - one of the species of the genus Freshwater gray sharks , the family Carcharhinidae . The view is known for the only museum specimen that was caught at the mouth of the Irrawaddy River in Myanmar . This shark has a thickened body of even gray color, a short rounded muzzle, small eyes and a wide first dorsal fin. Without an anatomical examination, it is difficult to distinguish it from other representatives of a kind. Almost nothing is known about her natural history, it is believed that she eats fish and multiplies by live birth . The International Union for Conservation of Nature (IUCN) rated the conservation status of this species as βEndangered Speciesβ, as its range is extremely limited, this species of sharks suffers from over-fishing and environmental degradation.
| Glyphis siamensis |
| Scientific classification |
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| No rank : | Bilateral symmetrical |
| Gender: | Freshwater Gray Shark |
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| International scientific name |
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Glyphis siamensis ( Steindachner , 1896) |
| Synonyms |
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Carcharias siamensis Steindachner, 1896 |
| Area |
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| Security status |
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Endangered SpeciesIUCN 3.1 Critically Endangered : 161611 |
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The only known specimen caught in the 19th century in the Irrawaddy River was described as Carcharias siamensis by the Austrian ichthyologist Franz Steindahner and was stored at the Annalen des Naturhistorischen Museums in Vienna [1] [2] . However, subsequent authors doubted the existence of this species, considering it as an unusual bull shark ( Carcharhinus leucas ), until in 2005 the taxonomist Leonard Compagno recognized it as a separate species belonging to the genus Glyphis [3] .
Glyphis siamensis lives in the Irrawaddy River Delta near Yangon in Myanmar , apparently in brackish waters with a muddy bottom and banks overgrown with mangroves [1] .
The only specimen of the shark Glyphis siamensis was an immature male 60 cm long, adult specimens were supposedly 1-3 m long. Like other freshwater sharks , Glyphis siamensis has a strong body with a high back, a rounded short muzzle and a wide mouth. Tiny eyes, nostrils small and wide apart. There are 29 upper and lower dentitions in the mouth, and there are grooves in the corners of the mouth. The upper teeth are wide, triangular, have a vertical set and serrated edges, the edges of the lower teeth are covered with small teeth, at the base there is a pair of small pointed protrusions [3] [4] . The first dorsal fin is wide, triangular, its base lies above the posterior margin of the pectoral fins. The second dorsal fin is 2 times lower in height than the first. The crest between the dorsal fins is absent. On the caudal margin of the anal fin there is a deep notch. The color is even grayish-brown, the belly is white, without marked marking of the fins. This shark most closely resembles the Indian gray shark ( Glyphis gangeticus ), but it has more vertebrae (209 versus 169) and fewer teeth (29/29 compared to 32β37 / 31β34) [3] [4] .
Small teeth of Glyphis siamensis suggest that she predominantly hunts fish, and her small eyes are adapted to live in very muddy waters. Presumably this is a live-bearing species of sharks [3] .
At the mouth of the Irrawaddy River, which is the only habitat for Glyphis siamensis , intensive artisanal fisheries are carried out, mainly using gillnets, as well as fishing rods and electricity. Habitat degradation, including water pollution and tree felling along the shores, poses a threat to the continued existence of this shark. The International Union for Conservation of Nature (IUCN) has included Glyphis siamensis in the list of endangered species. Over the past 100 years, not a single capture of a representative of this species of sharks has been documented [1] .
