When you thought it was safe to return to the water… did you know that certain sharks can survive and live in freshwater and salt? Some disbelieving tourists visiting South Africa were surprised while hippo-watching on a local river.
The average shark can’t live outside a saltwater environment any more than you could live in outer space. Still, quite a few species of sharks swim in freshwater for short periods, and some have nearly wholly adapted to a non-salty lifestyle. The bull shark is the most well-known of these species.
How can they move so seamlessly between the rivers and the sea? The short answer: they pee a lot. Bull sharks take in a lot of water and have an output of about 20 times the average saltwater shark. This is how they adapt to the freshwater rivers and streams. However, it does take a toll on their kidneys, which must work extra hard to keep up.
The spear tooth shark also inhabits the tropical rivers of northern Australia and Papua New Guinea. Not much is known about this critically endangered species, but they spend nearly all their time in the low salinity river waters, hunting in near-complete darkness. All in all, more than 400 species of sharks can move between saltwater and freshwater.
As for the hippos, they were not impressed. Hippos are responsible for more human deaths in Africa than any other wild animal. Sorry, Simba. Their stumpy-looking teeth are razor-sharp, and these innocent-looking animals are decidedly aggressive. Statistically speaking, while you might be more likely to encounter a shark (given that hippos are not found swimming in every ocean), you are far more likely to be killed by a hippo than a shark!
