There are only a few types of freshwater sharks in the world. These unique species have adapted to live in freshwater environments such as rivers and lakes.
It is exceptionally hard for sharks that have evolved in saltwater to transition to freshwater due to the lack of salt. Without retaining salt inside of their bodies, the sharks cells can rupture, causing them to bloat and die. Because of this, most saltwater shark species sink in freshwater.
However, certain species have developed the ability to retain salt and recycle it within their bodies, meaning there are types of freshwater sharks in lakes and rivers found all over the world. Here we take a look at several freshwater shark species and how to identify them.
The elusive Speartooth shark, or Glyphis can be found in both saltwater and freshwater environments. This incredibly rare type of freshwater shark is native to West Papua, Papua New Guinea and Northern Australia, residing most commonly on tropical riverbeds and fast flowing estuaries.
The Speartooth shark uses tidal currents to carry them upstream, which helps them preserve energy while feeding on fish and crustaceans.
Growing up to 9.8 feet in length, the characteristics of this sturdy shark species include a particularly wide head, flattened snout and small eyes.
Their mouths consist of approximately 29 rows of teeth on both the upper and lower jaws. While the Speartooth sharks teeth in the upper jaw are wide and serrated, the lower teeth are more narrow and spear-shaped, giving this type of freshwater shark it’s name.
The Ganges shark is a critically endangered marine species typically found in the Ganga, Hooghly, Mahanadi, and Brahmaputra rivers in India. This type of shark species is considered a true river shark, since they are only ever found in the depths of rivers and freshwater ecosystems.
The Ganges shark can be recognised by its solid grey or brown colouring. They have particularly small eyes due to the poor visibility of its habitat, they can also be identified by their two spineless dorsal fins and wide, round snout.
People often consider this species to be a threat to life, however these types of freshwater sharks are often mistaken for the vicious Bull shark. The Ganges shark is far less common, plus their teeth are specifically designed for puncturing fish as opposed to mammals, therefore human attacks are highly unlikely.
The deadly Bull shark is commonly found throughout the world in both salt and freshwater. With only 50% salt concentration in their blood, it is one of the most unique types of sharks as it is one of the only species which can survive in both freshwater and saltwater environments.
Robust, stocky and savage, this type of freshwater shark often resides where people think no danger exists. However, with their ability to swim thousands of miles upriver, the Bull shark is one of the most common freshwater sharks in lakes. They spend a lot of time in shallow waters where humans are more likely to frequent and are occasionally mistaken as food.
It can be quite challenging to identify a Bull shark, as their generic shark features are not particularly strong. This is why they are often confused with the Ganges River shark and even the Great White.
Unlike many other shark species, the Bull shark is one of the best freshwater sharks for aquariums and can live happily in captivity for many years!
Borneo River Shark
Found in the Kinabatangan River in Sabah, Malaysian Borneo, the Borneo River is one of the rarest types of freshwater sharks in the world. They derive from the Carcharhinidae or Requiem family of sharks, which are generally found in warm tropical waters.
This particular freshwater shark species is noticeably slim and small, growing to a maximum length of 2 feet. Their slate-grey colouring darkens at the dorsal fins which helps with identification. Because of their heavily serrated teeth, the Borneo River Shark will mostly feed on bony fishes such as sardines and tuna.
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