Biology
Several species of sharks have demonstrated the ability to sense magnetic fields (Kalmijn, 1978; Ryan, 1980; Klimley, 1993; 2002). The Ampullae of Lorenzini organ within sharks is used to detect weak electrical fields at short ranges. The detection range of this organ is effective only within inches, as sharks sense bioelectrical fields in the final stages of prey capture. The flux per unit area of certain permanent magnets, particularly Neodymium-Iron-Boride and Barium-Ferrite magnets, corresponds closely with the detection range of the Ampullae of Lorenzini. The fields generated by these permanent magnets (ferrite and rare-earth types) decrease at the inverse cube of the distance from the magnet to sharks and rays. Therefore, at distances of a few meters from the magnet, the field exerted is less than the Earth's magnetic field. Animals which lack that Ampullae of Lorenzini organ do not display aversive behavior in close proximity to the magnetic field, making this technology selective.
Read more about this topic: Magnetic Shark Repellent
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