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Zusammenfassung:
Natural magnetic iron-based minerals are observed in rocks and sediments. It is assumed that sediments carry a significant amount of magnetic minerals derived from dead organisms. To date, the organisms that biomineralize iron are forming magnetite or greigite crystals. These crystals are formed by a group of bacteria that utilize the magnetic torque acting on biomineralized iron nanoparticles, called magnetosomes, to align themselves in the Earth's magnetic field. In order to thrive, these bacteria follow a unique type of taxis referred to as magnetotaxis. Magnetotaxis relies on the interaction between an intracellular magnetic apparatus and the ambient magnetic field, chemical sensing, and motility provided by a flagellar apparatus. Evidence of magnetic minerals also exists in some eukaryotes. Iron plays a key role in metabolism and in the respiratory chain; however, in some animals it mineralizes magnetic iron oxides. It is assumed that those minerals can be utilized for sensing the Earth's magnetic field, an ability called magnetoreception. Magnetoreception allows the animals to use the Earth's magnetic field for orientation and navigation. This behavior is found in a large variety of animal phyla, especially in those who perform long-distance migrations or in those who live in environments that do not support visual orientation.
