German researchers have found cells in migratory animals which could contribute to the ability of the animals to sense the Earth’s magnetic field, and also explain why these animals are misled by high-tension power lines. The findings are reported in a release from the University of Munich.
The Earth is surrounded by a magnetic field created by the rotation of the planet’s iron core. Humans can detect this field with instruments like a compass, but some animal species appear to have the ability to sense the Earth’s magnetic field directly.
Finding the anatomical basis for this ability has remained a challenge to biologists, but scientists at the University of Munich, in collaboration with international partners, have found a type of cell that they believe may contribute to the animals’ perception of the magnetic field. The team has found cells in the lining of the olfactory cavity of trout which appear to convert magnetic responses into nervous system signals.
To find the cells, the team first separated the epithelium tissue into individual cells using enzymes. Then, by applying a rotating magnetic field to the mixture of many cell types, they were able to separate magnetically-responsive cells from the rest. Examining these cells closely, the team found that subjecting them to a magnetic field produced a stronger than expected response. They found tiny inclusions in the cells which appear to contain magnetic crystals, most likely composed of the mineral magnetite, that align themselves in response to the Earth’s magnetic field.
These magnetically-responsive inclusions are bound to the cell membrane, and thus as they move in response to magnetic-field changes, they are able to generate electrical potential changes on the cell’s surface, generating the signal necessary for the nervous system to take in information about the surrounding magnetic field.
Because the cells respond to magnetic fields surrounding them, the researchers believe that aberrations in navigation around structures such as high-voltage power lines, which generate magnetic fields, can be explained by the response of these magnetosensory cells to the artificial magnetic fields.
Migratory and herding animals such as cattle have been previously observed to alter their movements in response to such structures. Michael Winkelhofer, an author of the study, says, “This explains why low-frequency magnetic fields generated by powerlines disrupt navigation relative to the geomagnetic field and may induce other physiological effects.”
Winkelhofer also speculates that the findings might one day prove significant for human physiology as well.