South-Seeking Magnetic Bacteria

During the past few years, a wide variety of living organisms have been found which biologically synthesize the ferrimagnetic mineral, magnetite (Fe3O4) First discovered as a biogenic material in the teeth of a primitive mollusc, the chiton (Polyplacophora, Lowenstam 1962), it has since been found as an organic precipitate in magnetically sensitive honey bees (Gould, Kirschvink & Deffeyes, 1978), homing pigeons (Walcott, Gould & Kirschvink, 1979) and bacteria (Frankel, Blakemore & Wolfe, 1979). In all of these organisms (except the chiton), the magnetite is apparently used to orient with or detect the direction and intensity of the earth’s magnetic field (Kirschvink, 1979; Kirschvink & Gould, in review).