Sharks live in every ocean. Some like it hot (like the pacific sleeper shark), others adapted to freezing temperatures (like the greenland shark). Some doesn’t mind fluctuating saline levels (like the pyjama shark). But did you know that there are river sharks? That are sharks living solely in freshwater. One of them is the Ganges shark (Glyphis gangeticus).

FMIB 45519 Carcharinus gangeticus.jpeg
Ganges shark von Edgar Ravenswood Waite – Waite, Edgar R. (1921) Illustrated Catalogue of the Fishes of South Australia, Adelaide, Australia: G. Hassell & Son, Gemeinfrei, Link

This species of requiem shark lives in Indian rivers and has been accused to be a “man-eater”. But it has been most likely confused with bull sharks, since its slender teeth imply that its prey are rather small fish. It is a up to 6.6 ft – 2 m – long grey to brownish shark with minute, upward tilted eyes.

Pollution and utilization of its habitat and fishing pressure are dangers to the extremely rare Ganges shark. It is considered Critically endangered.

Recent genetic tests show that river sharks from Borneo (Borneo river shark) and Myanmar (Irrawaddy river shark) are the same species as the Ganges shark. Two recent gene flow events in the central Indo-Pacific (between Myanmar and India and Pakistan and Java) and a third, older event that resulted in the colonization of Australian rivers, prove that river sharks can migrate through saltwater. Perhaps all river sharks can live in the ocean, but choose to seek shelter for themselves and their young in rivers.

Sources: here and here

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