Out of more than 400 species of sharks inhabiting the world’s seas, scientists have identified 5 shark species that specialize in freshwater waters on rivers and lakes.
Until now, the research on river sharks in the world is very limited. Scientists have determined that the majority of river sharks belong to the 5 species of the Glyphis family. In addition, the possibility that there are many other shark species living in fresh water has not been discovered by researchers.
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River sharks live in freshwater waters of India, Southeast Asia and parts of Australia. However, it is rare for humans to see them with their own eyes.
Although they belong to the sharks family, river sharks seem harmless to humans. In addition, fishing activities, environmental pollution and the rapid development of people are seriously threatening the lives of the 5 shark species of the Glyphis family.
Normally, river sharks have a short body shape, wide mouth and small eyes. They can develop bodies up to 3m in length. In addition, river sharks often develop broad fins and look more like fish than sharks.
The jagged-toothed shark or Glyphis glyphis is one of the species capable of inhabiting mangrove and fast flowing rivers in northern Australia and New Guinea.
They develop large fins on the dorsal. The teeth grow deep under the jaws, quite small and look like a scoop, so they are named “Spear Shark”.
According to scientists, sharks often move when the tide changes to save energy for the body. Their daily food is fish and crustaceans. Like many sharks, they also give birth instead of laying eggs.
The International Association for the Conservation of Nature (IUCN) has listed the giant toothed shark on the list of endangered animals. Currently, there are only about 2,500 toothed sharks around the world and their lives are in danger due to the loss of habitat and indiscriminate human fishing.
Relatives of the spear shark including the northern river shark or the New Guinea river shark (scientific name: Glyphis garricki) and the Irrawaddy River shark (scientific name: Glyphis siamensis) — were discovered in a tour of the Irrawaddy River in Myanmar in the 19th century.
The Borneo river shark (scientific name: Glyphis fowlerae) is one of the most famous river sharks discovered in the 19th century.
According to IUCN shark researcher — Leonard Compagno, the scientific literature on habitat distribution and the biological characteristics of river sharks around the world is very limited. They are like “ghosts” that rarely appear and are scattered around. Therefore, detecting the presence of river sharks is considered a strange thing.
One of the rare and endangered river sharks is the Ganges shark (Glyphis gangeticus), which specializes in freshwater areas in eastern and northeastern India.
The Ganges shark is often mistaken for its appearance and structure similar to the cow shark (Carcharhinus leucas). They are known by many names such as river shark, Zambezi shark or Nicaragua shark.
Contrary to the dangers of bull sharks, the Ganges sharks appear quite little and pose no danger to humans.
Bull sharks typically live in shallow and warm waters along coasts and rivers around the world. They often swim very far and are known to be aggressive and opportunistic predators.
Sometimes, people can see a shark crawling away from the mainland of Indiana state and the Ohio River (USA). They are ranked at the top of the list of human attacks in the area near the coast.
It is worth mentioning that the bovine shark has evolved its ability to withstand life in freshwater by developing skills to limit the excretion of salt in the blood through the rectum. The gills and kidneys also help bovine sharks control salt absorption and excretion.
Usually bovine sharks hunt alone, but in some cases they go in pairs to hunt for more food. They mark their own territory and are ready to attack unauthorized intruders.
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