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A form of taxis characterized by a directional movement of an organism in response to a magnetic field


Taxis is a behavioral response of a cell or an organism to an external stimulus. The movement is characteristically directional. The movement may be positive or negative. A positive taxis is one in which the organism or a cell moves towards the source of stimulation (attraction). A negative taxis is when the organism or a cell moves away from the source of stimulation (repulsion).

One of the cell movements identified is magnetotaxis. Magnetotaxis is a directional movement of a cell in response to a magnetic field. The term was coined by R. P. Blakemore in 1975. He described certain motile aquatic bacteria that orient themselves according to the Earth's magnetic field. These bacteria are now referred to as magnetic bacteria (e.g. Magnetospirillum magnetotacticum). These organisms contain magnetosomes, which are membranous prokaryotic structures containing magnetite crystals that orient them towards geomagnetic fields. They were found to orient themselves magnetically even after death. Thus, this implicates that this response has not about sensing magnetic field. A true display of magnetotaxis has to show the ability to sense a magnetic field and coordinate their cell movement in response to it.

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