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Stephen Frink/Corbis

If you"re fear of sharks, there"s a simple way to protect against them: steer clear of shark-infested oceans and choose a freshwater spot instead. But why? What, exactly, is keeping these freshwater places shark-free? A new study provides one explanation: many sharks would certainly actually sink in fresh water.

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Scott Sutherland the the Weather Network reports top top a brand-new study that shows that sharks have actually trouble remaining afloat in fresher waters. A team of biologists from the joined States and Australia wonder why so few shark types can be uncovered in freshwater habitats. Prevailing theories said that something in the physical structure of sharks do it hard for them to survive in fresher waters.

The researchers used a hydromechanical model to study exactly how shark physiology affects buoyancy. Together Sutherland explains, sharks absence a swim bladder—the gas-filled body organ that helps various other bony fish float. However they do have actually extra big livers, which provide some buoyancy and help save them sinking to the s floor.

But new water alters how lot buoyancy the shark"s liver deserve to provide. The researchers found that when sharks swimming in fresh water, they room two to three times less buoyant than as soon as they swimming in salt water. In stimulate to keep afloat the same method they perform in salt water, sharks would certainly need livers eight times as large—unrealistic because that an body organ that’s already the biggest in a shark’s body.

“For reference, the liver of a fully-grown, 1-ton good White Shark have the right to tip the scale at approximately 250 kilograms - over 3.5x the mass of the median male human,” note Sutherland. That means that the shark would have actually support a two-ton liver just to float in fresh water—that’s two times its currently mass.

So it appears that ocean-loving sharks aren’t likely to it is adapted to fresh water any kind of time soon. However don’t think that means you’ll never ever see a fin in new water. There space a few river sharks, like bow sharks, the have adjusted to much less salty environments; their livers, the study found, are much less dense than those of naval sharks, which helps them stay afloat.

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Though the number the freshwater sharks are dwindling, they still can threaten humans. On 2nd thought, probably the kiddie swimming pool isn’t such a negative swimming clues after all.