November 19, 2008

Magnet Repel Sharks!

Since 2001, SharkDefense has been working on a chemical shark repellent. According to Herrmann, he and Stroud were playing around with powerful rare-earth magnets in 2005, when he dropped one next to their shark research tank in Oak Ridge, New Jersey. The lemon and nurse sharks inside instantly darted to the opposite wall.

In testing at the Bimini Biological Research Station shark lab in the Bahamas, Stroud and Herrmann have found that sharks dramatically avoid magnets made from neodymium, iron and boron. The magnets even rouse sharks from tonic immobility, a coma-like state induced by turning them upside down.

A lemon shark is instantly repelled by Ocean Magnetics' unnamed "mystery metal," even when the metal is hidden behind a plastic barrier.

Herrmann says he and Stroud think the magnets overload a shark's ampullae of Lorenzini, small vesicles and pores around the head that form part of a subcutaneous sensory network. What's more, he says a metal with similar electropositive qualities also appears to affect sharks the same way. Hermann preferred to keep the identity of that metal secret for now.

A line of magnets (underneath the black line in the center) keeps a group of juvenile lemon sharks on one side of a test tank.

Divers and swimmers may thrill to the idea of shark safeguards. However, before you rush out to buy neodymium magnets to create your own shark-repelling gear, Herrmann cautions that the magnets appear to have an effective range of only 10 inches. Also, you'd need to align the magnetic poles outward and keep the magnets from clicking together, and once you had the necessary 10 to 20 pounds of magnets all over your body, you'd sink. So, at a cost of about $5 a magnet, you could

A lemon shark with tonic immobility (a comatose state induced by turning it upside-down) is roused by bringing a magnet near its head.

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