Physics Question #2300

Ed Kasica, a 12 year old male from Oldsmar, florida asks on October 11, 2004,

Why does a magnetic field in the form of a bar magnet effect the movement of a planaria? Does it have iron from its enviroment in its body?

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The answer

James Livingston answered on October 13, 2004

We do not know for sure. Magnetic fields have been shown to affect the motion of many animals. In some cases, as in magnetotactic bacteria, the animal contains a significant volume of a magnetized magnetic compound such as iron oxide, rather like an internal compass, and the action of a magnetic field on those magnetic particles produces a force or torque that can affect the animal's motion. Similar but less pronounced effects have been observed in larger animals, but the mechanism has yet to be determined.

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