Be Careful Where You Swim: Some Sharks Can Live in Freshwater Too

For years, sharks have remained some of the most terrorizing creatures in the ocean. Their aggressive nature and razor-sharp teeth can trigger a great deal of fear among beachgoers. However, some species actually have the ability to survive in freshwater.

Believe or not, it’s not uncommon to spot sharks swimming in the Mississippi River. They have also taken up residence in Central America’s Lake Nicaragua. This is especially true for the bull shark, which is considered to be one of the most dangerous species alive. So, what enables bull sharks to thrive in freshwater?

Because far less salt is present in lakes and rivers, the typical shark won’t be able to survive. Although bull sharks are naturally at home in the sea, unique kidneys enable them to adapt to freshwater environments. Their kidneys essentially recycle the salt content within their bodies through a process called osmoregulation. Bull sharks also have special glands, which help further with salt retention.

This special survival adaptation serves more than one purpose. Being able to thrive in different types of water sources gives bull sharks a key advantage. By raising their young in lakes opposed to the ocean, bull sharks can reduce the threat of certain predators.