Higher order taxa:
Bacteria; Proteobacteria; unclassified Proteobacteria
Magnetococcus sp. MC-1, environmental samples. (source NCBI Taxonomy)
Description and Significance
Magnetococcus, also known as magnetotactic bacteria, are the smallest organisms that use a navigational method by using the earth's geomagnetic field to develop an internal compass. Magnetotactic bacteria were discovered in 1975 by Richard P. Blakemore when he noticed that some of the bacteria that he observed under the microscope always moved to the same side of the slide. These bacteria are able to move in a particular direction because they make tiny, iron-containing magnetic particles. Each of these particles is a magnet with a north pole and a south pole. The bacteria arrange these tiny magnets in a line to make one long magnet. They use this magnet as a compass to align themselves to the earth's geomagnetic field.
Magnetotactic bacteria use their magnetic compass to tell them which way is down in an aquatic environment. These bacteria don't like oxygen and move from areas with high oxygen towards area with low or no oxygen. The level of oxygen decreases as one moves deeper into the water so magnetotactic bacteria live in the deeper parts of their aquatic environments, using their compass to help them.
It has to do with the direction of the geomagnetic field. In the Northern Hemisphere; the geomagnetic north actually points down at an angle. So, magnetotactic bacteria that are aligned to this field are also pointing down. By moving north along this field, they move deeper into the water, and into areas with less oxygen. Interestingly, in the Southern Hemisphere, the geomagnetic north actually points up and at an angle. So, magnetotactic bacteria in this half of the world are "south-seeking", which points them downward. At the equator, the geomagnetic north doesn't point up or down, so the magnetotactic bacteria found there are a mixture of north-seeking and south-seeking bacteria.