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A river shark, as far as is known, is a species of shark that lives in freshwater rivers. The six known species of river sharks belong to the genus Glyphis, which is part of the family Carcharhinidae. River sharks remain one of nature’s great mysteries; only a handful of river sharks have been caught and few have been observed in the wild. Scientists assume that due to the rare sightings, most river shark species are likely to be in danger of extinction.
As members of the Carcharhinidae family, river sharks share many of the same characteristics as their ocean relatives. They have small round eyes and their upper teeth are wide and serrated. His nose is short and rounded, with widely spaced nostrils. They also have a prominent dorsal fin. They are the most similar to whale sharks, which belong to the genus Carcharhinus. The whale shark has a lower dentition that protrudes even when the jaw is closed and a second dorsal fin that is almost half the size of the other dorsal fin.
In total, there are six documented species of the Glyphis genus: Glyphis gangeticus, better known as the Ganges shark; Glyphis glyphis, known as the spear tooth shark; Glyphis siamensis, known as the Irrawady River shark; Glyphis species A; Glyphis species B, also known as the Borneo River shark; and Glyphis C species. Ganges and Irrawady sharks are named after the rivers in which they were documented. The Glyphis River shark species has been documented in several rivers in Australia.
Very little is known about the ecology and habits of river sharks, due to rare sightings and scant documentation. River sharks are presumed to be primarily fish eaters, although this is not known for certain. Nothing substantial is known about their breeding habits.
Sightings are so rare that at one point the Ganges shark was not sighted for about a century. Officially documented sightings of the speartooth shark are even rarer. Species of river sharks are considered endangered and some, such as Speartooth and Irawaddy, possibly extinct, although it is very likely that such sharks have been seen but confused with other species of river sharks.
The bull shark, also in the family Carcharhinidae, is sometimes confused with a river shark. Bull sharks have been known to swim for miles in freshwater streams where they can live for years. However, the bull shark’s primary habitat and only breeding ground is the ocean.