Editing Ganges shark (section)

==Habitat and ecology==
[[File:Carcharias_gangeticus_Day_187.jpg|thumb]]
''G. gangeticus'' is known to inhabit only freshwater, inshore marine, and estuarine systems in the lower reaches of the Ganges-Hooghly River system. Their feeding habits are mostly unknown. The shark's small eyes and slender teeth suggest that it is primarily a fish-eater and is adapted to turbid water.<ref name="Compagno1997"/> With such limited visibility typical of many tropical rivers and estuaries, other senses − such as hearing, smell, and [[electroreception]] − are likely used for predation.<ref name="Martin"/> Because its eyes are tilted towards its back rather than to the sides or bottom (as is the case in most carcharhinids), the shark may swim along the bottom and scan the water above it for potential prey back-lit by the sun.<ref name="Compagno1984"/> However, in the Bay of Bengal, ''G. gangeticus'' was found to feed heavily on dasyatid [[stingray]]s, which spend much of their time on the bottom.<ref>{{cite book |last=Roberts |first=T. R. |title='Debunking the mythology of the so-called freshwater shark of the Ganges. Glyphis gangeticus (Elasmobranchii, Carcharhinidae)'. In: 7th Indo-Pacific Fish Conference. Howard International Hotel, Taipei, Taiwan. Academica Sinica, Taipei, Taiwan |year=2005 |publisher=Ichythological Society of Taiwan |location=Taipei, Taiwan}}</ref>

=== Reproduction ===
It is probably [[viviparous]], with a yolk-sac placenta (speculation through analogy to related species of carcharhinids). The litter size and gestation period are unknown.<ref name=Compagno1997/> However, their life history cycle is probably similar to other river sharks, characterized by long gestation, slow growth, delayed maturity, and small litter size. These factors make the Ganges shark populations vulnerable to even relatively low levels of exploitation, such as sport angling or gill netting.<ref name=Martin/>

=== Possibility of migration ===
Some researchers consider ''G. gangeticus'' to be [[Fish migration|amphidromous]], covering more than {{convert|100|km|abbr=on}} in both directions.<ref>{{cite journal |last1=Hărșan |first1=R. |last2=Petrescu-Mag |first2=I. V. |title=Endangered fish species of the world – a review |journal=AACL Bioflux |year=2008 |volume=1 |issue=2 |pages=193–216}}</ref> However, this is not thought to be for breeding, as the case in anadromous and catadromous species.<ref name="Ref. 51243">{{cite book |last=Riede |first=K. |title=2004 Global register of migratory species - from global to regional scales. Final Report of the R&D-Projekt 808 05 081. |year=2004 |publisher=Federal Agency for Nature Conservation |location=Bonn, Germany |pages=329}}</ref> The presence of newborn individuals in the Hooghly River suggests that the young may be born in fresh water.<ref name="MSIP"/>

A specimen photographed in 2011 by natural history journalist Malaka Rodrigo at [[Negombo]] fish market in Sri Lanka prompted researcher Rex de Silva to speculate on whether the species could occasionally be carried south of its normal range by ocean currents. However, only the head of the shark appears in the photo. Leading shark expert [[Leonard Compagno]] emphasised the need to check the dentition and the dorsal fin proportions to confirm the specimen as ''G. gangeticus'', stating that it could also be one of the four other named species.<ref>{{cite journal |last=de Silva |first=Rex I. |title=Does the Ganges shark ''Glyphis gangeticus'' stray to Sri Lanka? |journal=Journal of the Bombay Natural History Society |date=May–August 2011 |volume=108 |issue=2 |page=136 |url=https://www.researchgate.net/publication/215535273}}</ref>

=== Specimens ===
''G. gangeticus'' was originally known only from three 19th-century museum specimens, one each in the [[National Museum of Natural History]] in Paris, [[Natural History Museum, Berlin]] in Berlin, and the [[Zoological Survey of India]] in [[Calcutta]].<ref>{{cite book |last1=Baillie |first1=Jonathan |last2=Groombridge |first2=Brian |title=1996 IUCN Red List of Threatened Animals |publisher=International Union for Conservation of Nature |location=Gland, Switzerland |isbn=9782831703350|year=1996 }}</ref> No records exist between 1867 and 1996, and the 1996 records have not been confirmed as ''G. gangeticus''. A specimen collected {{convert|84|km|abbr=on}} upstream of the mouth of the Hooghly River at [[Mahishadal]] in 2001 was identified as ''G. gangeticus'', but on photographs of the jaw only.<ref name=Compagno1984/> If ''Carcharias murrayi'' (Günter, 1887) can be considered a junior synonym of this species, one was found near [[Karachi]], Pakistan. However, the [[holotype]] was apparently lost or misplaced in the [[British Museum of Natural History]].<ref name=Compagno1997/>

One female specimen was recorded at Sassoon Docks in [[Mumbai]], India in February 2016, measuring {{cvt|266|cm|abbr=on}} [[fish measurement|total length]]. It was caught in the [[Arabian Sea]].<ref>{{Cite journal|last1=Jabado|first1=R. W.|last2=Kyne|first2=P. |last3=Nazareth|first3=E.|last4=Sutaria|first4=D. N.|date=2018|title=A rare contemporary record of the Critically Endangered Ganges shark ''Glyphis gangeticus'' |journal=Journal of Fish Biology|language=en|volume=92|issue=5|pages=1663–1669|doi=10.1111/jfb.13619|pmid=29611178|bibcode=2018JFBio..92.1663J |issn=1095-8649}}</ref>

=== Molecular biology ===
''Glyphis'' species, like other sharks, exhibit a very slow rate of genetic change. This makes them even more vulnerable to becoming extinct, as they are unable to adapt to the rapid and extreme changes caused by humans to their environment.<ref name="Martin"/>

As only a few specimens exist, naturally little material available is for genetic sampling. However, two websites list records for ''G. gangeticus'':

The Barcode of Life Data Systems (BOLDS) Stats website<ref>{{cite web |title=Glyphis gangeticus |publisher=Barcode of Life Data Systems |url=http://www.boldsystems.org/index.php/Taxbrowser_Taxonpage?taxid=179821 |access-date=6 December 2012}}</ref> lists one record:<br />
Public Records: 0<br />
Specimens with Barcodes: 1<br />
Species With Barcodes: 1

The NCBI Taxonomy database has one record of mitochondrial genetic material (1,044 base pairs of linear DNA):<br />
''Glyphis gangeticus'' bio-material GN2669,<ref>{{cite web|title=Glyphis gangeticus|date=31 July 2012|url=https://www.ncbi.nlm.nih.gov/nuccore/397768867|publisher=NCBI|access-date=10 December 2012}}</ref> reported in a 2012 paper on DNA sequencing in shark and ray species.<ref>{{cite journal |last1=Naylor |first1=G. J. P. |last2=Caira |first2=J. N. |last3=Jensen |first3=K. |last4=Rosana |first4=A. M. |last5=White |first5=W. T. |last6=Last |first6=P. R. |title=A DNA Sequence-Based Approach To the Identification of Shark and Ray Species and Its Implications for Global Elasmobranch Diversity and Parasitology |journal=Bulletin of the American Museum of Natural History |year=2012 |volume=367 |pages=1–262 |doi=10.1206/754.1 |hdl=2246/6183 |s2cid=83264478 |url=https://www.biodiversitylibrary.org/bibliography/195492 }}</ref>