'Superhuman Animals': Woman Tests Shark Repellent In Shark-Infested Waters

On "Superhuman Animals," Dr. Helen Czerski dove into shark-infested waters using only a certain smell as her defense. "Their noses are detecting the minute chemical cues I give off as I move through the water," Dr. Czerski explains.

Marine biologist Dr. Patrick Rice is also helping to develop the shark repelling scent called a necromone.

A necromone is a chemical signal that tells sharks there are other predators in the area. It's also the smell of dead shark, which is a sure sign for other sharks that danger is around. When sharks smell it, they are hard-wired to flee.

As Shark Defense.com notes, it's believed this is a response they've had since prehistoric times. It evolved at a time when sharks weren't top predators -- they were just little things in the big, bad sea. Imagine that.

To catch more episodes of "Superhuman Animals" you can tune in Tuesday nights at 8/7c on BBC America.

Speaking of sharks, have you ever seen the creepy 'cookiecutter'?

More to see:
Shark kills man in Australia despite rescue bid
Great white shark attacks two off coast of Massachusetts
Massive whale shark crashes into diver