What is a River Shark?

A river shark, as far as anyone knows, is a kind of shark that lives in freshwater rivers. All six known species of river shark belong to the Glyphis genus, which is part of the Carcharhinidae family. River sharks remain one of the great mysteries of nature; only a handful of river sharks have ever been captured, and few have ever been observed in their natural habitat. Scientists presume that, due to rare sightings, most river shark species are likely endangered.

As members of the Carcharhinidae family, river sharks share many of the same features of their ocean relatives. They have small, beady eyes, and their upper set of teeth is wide and serrated. Their nose is short and rounded, with nostrils spread wide apart. They also have a prominent dorsal fin. They bear the most resemblance to whaler sharks, which belong to the genus Carcharhinus. Whaler sharks have a lower set of teeth that protrude even when the jaw is closed, and they have a second dorsal fin which is roughly half the size of the other dorsal fin.

In all, there are six documented species of the Glyphis genus: Glyphis gangeticus, better known as the Ganges shark; Glyphis glyphis, known as the Speartooth shark; Glyphis siamensis, known as the Irrawady River Shark; Glyphis species A; Glyphis species B, also known as the Borneo River Shark; and Glyphis species C. The Ganges and the Irrawady sharks are named for the rivers in which they've been documented. The Glyphis river shark species have been documented in multiple rivers around Australia.

Very little is known about the ecology and habits of river sharks, due to rare sightings and scarce documentation. It's presumed that river sharks are primarily fish-eaters, although that's not known for certain. Nothing substantial is known about their breeding habits.

Sightings are so few and far between that at one point the Ganges shark wasn't sighted for roughly a century. Officially documented sightings of the Speartooth Shark are even rarer. River shark species are considered endangered, and some, such as the Speartooth and Irawaddy, possibly extinct—although it's very likely that such sharks may have been seen but mistaken for other river shark species.

The bull shark—also of the Carcharhinidae family—is sometimes confused for a river shark. Bull sharks have been known to swim for miles up freshwater streams, where they can live for years. The bull shark's main habitat and only breeding ground, however, is in the ocean.

A river shark is a type of freshwater shark belonging to the genus Glyphis, which is known for its ability to live in rivers and estuaries. Unlike most sharks that inhabit marine environments, river sharks have adapted to murky, less saline waters and are among the few shark species that can thrive in freshwater ecosystems.

River sharks are found in select river systems in Asia and Oceania. For instance, the Ganges shark is native to the Ganges River in India, while the Northern river shark and the Speartooth shark inhabit rivers and coastal areas in Australia and New Guinea. Their habitats are often remote and poorly surveyed, contributing to their elusive nature.

There are currently five recognized species of river sharks. These include the Ganges shark, the Northern river shark, the Speartooth shark, the Irrawaddy river shark, and the New Guinea river shark. Due to their cryptic nature and the difficulty in studying them, our understanding of these species is limited.

Yes, river sharks are considered to be among the most endangered of all sharks. According to the International Union for Conservation of Nature (IUCN), species like the Ganges shark are listed as Critically Endangered, facing threats from habitat degradation, pollution, and overfishing in their already restricted ranges.

River sharks are carnivorous and their diet likely consists of small fish and invertebrates found within their riverine habitats. Due to the turbid waters they often inhabit, river sharks may rely on their heightened senses, such as electroreception, to locate prey.

River sharks differ from other sharks in their unique adaptations to freshwater environments. They have a more streamlined body to navigate strong river currents and possibly a higher tolerance for variations in salinity. Additionally, they are generally more elusive and less studied than their marine counterparts, making them a subject of great interest and concern for conservationists.