Migratory animals utilize the Earth’s magnetic field in order to find their way across large distances. The exact biological source for this ability has previously been unknown, but according to new research it’s been located.
The ‘internal compass needles’ for the perception of the field has been found to be a group of specialized cells in the olfactory epithelium, this helps to explain why high-tension cables ‘perturb the magnetic orientation’.
Even though it’s an ability shared by many animal species, efforts to pinpoint the biological source of the ability to sense of the geomagnetic field, and its exploitation for spatial orientation, have so far failed. Identifying the cells that detect the field and convert the information into nerve impulses has been elusive.
“The field penetrates the whole organism, so such cells could be located almost anywhere, making them hard to identify,” says LMU geophysicist Michael Winklhofer. Along with an international team of researchers, he has located the magnetosensory cells in the olfactory epithelium of the trout.
“The researchers first used enzymes to dissociate the sensory epithelium into single cells. The cell suspension was then stimulated with an artificial, rotating magnetic field. This approach enabled the team to identify and collect single magnetoresponsive cells, and characterize their properties in detail.”
“Much to Winklhofer’s surprise, the cells turned out to be more strongly magnetic than previously postulated – a finding that explains the high sensitivity of the magnetic sense.”
“The cells sense the field by means of micrometer-sized inclusions composed of magnetic crystals, probably made of magnetite. The inclusions are coupled to the cell membrane, which is necessary to change the electrical potential across the membrane when the crystals realign in response to a change in the ambient magnetic field.”
“This explains why low-frequency magnetic fields generated by powerlines disrupt navigation relative to the geomagnetic field and may induce other physiological effects,” says Winklhofer.
The new research may lead to advances in the fields of applied science — for example, possibly in the development of highly sensitive magnetometers. It also raises the interesting question of whether “human cells are capable of forming magnetite and if so, how much.”
“If the answer to the question is yes”, Winklhofer speculates, “intracellular magnetite would provide a concrete physiological substrate that could couple to so-called electrosmog”.
Author’s Note: Electrosmog is a term used for electromagnetic pollution. Here’s an interesting article from msnbc on the subject.