River shark

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River shark
Temporal range: Miocene – Recent [1]
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Speartooth shark melbourne.jpg
Speartooth shark (Glyphis glyphis) at the Melbourne Aquarium
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Subdivision: Selachimorpha
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Glyphis
Agassiz, 1843
Type species
Carcharias (Prionodon) glyphis
Müller & Henle, 1839

Glyphis is a genus in the family Carcharhinidae, commonly known as the river sharks. They live in rivers or coastal regions in and around south-east Asia, Africa and parts of Australia.

Contents

Taxonomy

This genus contains only three extant species. Further species could easily remain undiscovered, due to their secretive habits. [2] This genus was thought to contain five different species, but recent studies on molecular data revealed that the species Glyphis gangeticus has an irregular distribution in the Indo-West Pacific region. [3] The genus Glyphis is closest to the genus Lamiopsis.

Species

The recognized species in this genus are: [4]

Distribution and habitat

Their precise geographic range is uncertain, but the known species are documented in parts of Africa, South Asia, Southeast Asia, New Guinea [5] and Australia. Of the three currently described species, the Ganges shark is restricted to freshwater, while the northern river shark and the speartooth shark are found in coastal marine waters, as well. While the bull shark (Carcharhinus leucas) is sometimes called both the river shark and the Ganges shark, it should not be confused with the river sharks of the genus Glyphis. River sharks evolved to have their offspring in freshwater, therefore, making them safe to roam in the water while other sharks are able to survive in saltwater.

Conservation

River sharks remain very poorly known to researchers. River sharks were thought to be extinct until the end of the 20th century, when small populations were discovered in Borneo and Northern Australia. [6] Now, they face a critically endangered status as they are so poorly studied, and people know very little about their population and life history.

Glyphis gangeticus uses the Ganges River as nursery grounds and the birthplace of many Ganges shark offspring, however the population has been severely diminished owing to a long history of fishing and other pollution-related issues in the Northern Arabian Sea. Additionally, India, where the Ganges river flows, is reported to be one of the top three greatest shark and ray capturers in the world, accounting for up to 9 percent of reported global landings (Jabado et al., 2018). They are reported from the Zambezi river in Africa. They have been found in nine different tidal areas, which consist of muddy waters with a low salinity. Their placement in connection to coastal marine waters indicates that they are usually born around October. [5]

Images

Commons-logo.svg Media related to Glyphis at Wikimedia Commons

Related Research Articles

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Requiem sharks are sharks of the family Carcharhinidae in the order Carcharhiniformes. They are migratory, live-bearing sharks of warm seas and include such species as the bull shark, lemon shark, blacktip shark, and whitetip reef shark.

<span class="mw-page-title-main">Lamniformes</span> Order of sharks

The Lamniformes are an order of sharks commonly known as mackerel sharks. It includes some of the most familiar species of sharks, such as the great white as well as less familiar ones, such as the goblin shark and megamouth shark.

<span class="mw-page-title-main">Carpet shark</span> Order of sharks

Carpet sharks are sharks classified in the order Orectolobiformes. Sometimes the common name "carpet shark" is used interchangeably with "wobbegong", which is the common name of sharks in the family Orectolobidae. Carpet sharks have five gill slits, two spineless dorsal fins, and a small mouth that does not extend past the eyes. Many species have barbels.

<span class="mw-page-title-main">Ganges river dolphin</span> Species of toothed whale

The Ganges river dolphin is a species of freshwater dolphin classified in the family Platanistidae. It lives in the Ganges and related rivers of South Asia, namely in the countries of India, Nepal, and Bangladesh. It is related to the much smaller Indus river dolphin which lives in the Indus River in Pakistan and the Beas River of northwestern India.

<span class="mw-page-title-main">Ganges shark</span> Species of shark

The Ganges shark is a critically endangered species of requiem shark found in the Ganges River and the Brahmaputra River of India and Bangladesh. It is often confused with the more common bull shark, which also inhabits the Ganges River and is sometimes incorrectly referred to as the Ganges shark. The genus is currently considered to contain three recent species; genetic evidence has shown that both the Borneo river shark and Irrawaddy river shark should be regarded as synonyms of the Ganges shark, expanding the range of the species to Pakistan, Myanmar, Borneo, and Java. While the other members of the genus Glyphis occur in coastal marine waters as well as rivers, the Ganges shark is found only in fresh water, making it the world's only exclusively freshwater shark. The species remains poorly known and very rare.

<i>Echinorhinus</i> Genus of sharks

Echinorhinus is the only extant genus in the family Echinorhinidae.

John Andrew Frank Garrick was a New Zealand ichthyologist.

<span class="mw-page-title-main">Speartooth shark</span> Species of shark

The speartooth shark is a rare species of river shark, belonging to the family Carcharhinidae. It inhabits coastal marine waters and tidal reaches of large tropical rivers in northern Australia and New Guinea. Despite being a member of the river shark genus, it is also found in near-shore marine waters, favoring highly turbid environments over a wide range of salinities. This robustly built, gray-colored shark is characterized by a short and broad snout, tiny eyes, a relatively large second dorsal fin, and a black blotch beneath each pectoral fin near the tip. Another identifying trait is its teeth, which are large, triangular, and serrated in the upper jaw and narrow, spear-like, and serrated only near the tips in the lower jaw. Adults grow to about 2.6 m (8.5 ft) long.

<span class="mw-page-title-main">Hardnose shark</span> Species of shark

The hardnose shark is a species of requiem shark, in the family Carcharhinidae, so named because of the heavily calcified cartilages in its snout. A small bronze-coloured shark reaching a length of 1.1 m (3.6 ft), it has a slender body and a long, pointed snout. Its two modestly sized dorsal fins have distinctively elongated rear tips. The hardnose shark is widely distributed in the western Indo-Pacific, from Kenya to southern China and northern Australia. It inhabits warm, shallow waters close to shore.

<span class="mw-page-title-main">Pigeye shark</span> Species of shark

The pigeye shark or Java shark is an uncommon species of requiem shark, in the family Carcharhinidae, found in the warm coastal waters of the eastern Atlantic and western Indo-Pacific. It prefers shallow, murky environments with soft bottoms, and tends to roam within a fairly localised area. With its bulky grey body, small eyes, and short, blunt snout, the pigeye shark looks almost identical to the better-known bull shark. The two species differ in vertebral count, the relative sizes of the dorsal fins, and other subtle traits. This shark typically reaches lengths of 1.9–2.5 m (6.2–8.2 ft).

<span class="mw-page-title-main">Pondicherry shark</span> Species of shark

The Pondicherry shark is an extremely rare species of requiem shark, in the family Carcharhinidae. A small and stocky gray shark, it grows not much longer than 1 m (3.3 ft) and has a fairly long, pointed snout. This species can be identified by the shape of its upper teeth, which are strongly serrated near the base and smooth-edged near the tip, and by its first dorsal fin, which is large with a long free rear tip. Furthermore, this shark has prominent black tips on its pectoral fins, second dorsal fin, and caudal fin lower lobe.

<span class="mw-page-title-main">Barbeled houndshark</span> Species of shark

The barbeled houndshark is a species of ground shark and the only member of the family Leptochariidae. This demersal species is found in the coastal waters of the eastern Atlantic Ocean from Mauritania to Angola, at depths of 10–75 m (33–246 ft). It favors muddy habitats, particularly around river mouths. The barbeled houndshark is characterized by a very slender body, nasal barbels, long furrows at the corners of the mouth, and sexually dimorphic teeth. Its maximum known length is 82 cm (32 in).

<span class="mw-page-title-main">Northern river shark</span> Species of shark

The northern river shark or New Guinea river shark is a species of requiem shark, in the family Carcharhinidae, found in scattered tidal rivers and associated coastal waters in northern Australia and in Papua New Guinea. This species inhabits areas with poor visibility, soft bottoms, and large tides, with immature sharks ranging into fresh and brackish water. It is similar to other river sharks in having a stocky grey body with a high back, tiny eyes, and broad fins. It measures up to 2.5 m (8.2 ft) long.

<i>Carcharias</i> Genus of sharks

Carcharias is a genus of mackerel sharks belonging to the family Odontaspididae. Once bearing many prehistoric species, all have gone extinct with the exception of the critically endangered sand tiger shark.

<i>Rhinobatos</i> Genus of cartilaginous fishes

Rhinobatos is a genus of fish in the Rhinobatidae family. Although previously used to encompass all guitarfishes, it was found to be polyphyletic, and recent authorities have transferred many species included in the genus to Acroteriobatus, Glaucostegus, and Pseudobatos.

<i>Pristis</i> Genus of cartilaginous fishes

Pristis is a genus of sawfish of the family Pristidae. These large fish are found worldwide in tropical and subtropical regions in coastal marine waters, estuaries, and freshwater lakes and rivers. Sawfish have declined drastically and all species are considered critically endangered today.

References

  1. 1 2 "Glyphis Agassiz 1843 (river shark)". Fossilworks.
  2. 1 2 3 Li, Chenhong; Corrigan, Shannon; Yang, Lei; Straube, Nicolas; Harris, Mark; Hofreiter, Michael; White, William T; Naylor, Gavin J. P (2015). "DNA capture reveals transoceanic gene flow in endangered river sharks". Proceedings of the National Academy of Sciences. 112 (43): 13302–7. Bibcode:2015PNAS..11213302L. doi: 10.1073/pnas.1508735112 . PMC   4629339 . PMID   26460025.
  3. Jabado, R. W.; Kyne, P. M.; Nazareth, E.; Sutaria, D. N. (2018). "A rare contemporary record of the Critically Endangered Ganges shark Glyphis gangeticus". Journal of Fish Biology. 92 (5): 1663–1669. Bibcode:2018JFBio..92.1663J. doi:10.1111/jfb.13619. ISSN   1095-8649. PMID   29611178.
  4. Bailly, Nicolas (2014). "Glyphis Agassiz, 1843". WoRMS. World Register of Marine Species . Retrieved 6 July 2023.
  5. 1 2 White WT; Appleyard SA; Sabub B; Kyne PM; Harris M; Lis R; et al. (October 7, 2015). "Rediscovery of the Threatened River Sharks, Glyphis garricki and G. glyphis, in Papua New Guinea". PLoS ONE . 10 (10): e0140075. Bibcode:2015PLoSO..1040075W. doi: 10.1371/journal.pone.0140075 . PMC   4596488 . PMID   26445387.
  6. Li, Chenhong; Corrigan, Shannon; Yang, Lei; Straube, Nicolas; Harris, Mark; Hofreiter, Michael; White, William T.; Naylor, Gavin J. P. (2015). "DNA capture reveals transoceanic gene flow in endangered river sharks". Proceedings of the National Academy of Sciences of the United States of America. 112 (43): 13302–13307. Bibcode:2015PNAS..11213302L. doi: 10.1073/pnas.1508735112 . ISSN   0027-8424. JSTOR   26465770. PMC   4629339 . PMID   26460025.