A magic trick only looks amazing until you know how it works. So is true with devices that repel aggressive sharks. The latest is called Sharkbanz, which repelled hungry bull sharks with a magical bracelet in a new video.

Sharkbanz works through an embedded magnet which sends out a field that sharks can sense. Similar to other shark deterring devices, Sharkbanz exploits a special trait in sharks for detecting electric current. They use this keen sense to track down prey even when it’s hiding in the weeds or mud, but for scientists working on devices to keep them away from surfers and swimmers it’s this trait that can be exploited.

In other shark deterring devices, an electrical current is emitted, which makes the products somewhat bulky. A device called SurfSafe is specifically designed to be embedded in surf boards. With Sharkbanz, it’s much smaller and lighter.

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Recently the company released a video showing just how effective its Sharkbanz ankle bracelet is among a school of hungry bull sharks. Around the world, bull sharks represent one of the biggest threats to swimmers because of their aggressive nature and near shore proximity. 

In the video, the sharks approach the bait and then turn away after sensing the bracelet. Later, once the bracelet is removed, a shark tears at the foot in just a few minutes.

Photo credit: Sharkbanz @Facebook