Searching for Magnetoreceptors in Birds
The theory that navigational skills in some birds may be influenced by iron particles in their beaks reacting to the magnetic field of the earth, has recently been refuted by scientists at Vienna’s Institute of Molecular Pathology. Acknowledging that the new discovery was somewhat disappointing, molecular biologist David Keays noted that the mystery of how animals detect magnetic fields had become even more mysterious.
Using 3D scanners on slivers of pigeon beak, researchers found that the particles which had previously been thought to react with the earth’s magnetic field were in fact macrophages with normal amounts of organic iron to protect the birds from infection. These cells have no ability to produce electric signals to communicate with brain cells and are therefore unable to influence the pigeon’s behavior. These same cells were also found in other parts of the bird’s body and are found in other animals, particularly in the spleen, lungs, and skin, where they play an essential role in recycling iron from red blood cells and fight against infection. The findings were confirmed by scientists from the University of Western Australia – Jeremy Shaw and Martin Saunders – who were also working on the study.
Keays was reported as saying that the new discovery should not be seen as a set-back as it puts scientists on the right path to finding magnetic cells. The general consensus remains that birds, and a significant number of other animals, detect the magnetic field of the earth and use it for navigation. So it stands to reason that they must have cells facilitating this, although in the case of birds, it has been suggested they may make use of landmarks or sunlight for navigation as well.
Scientists will continue in their quest to understand how migratory birds interact with the earth’s magnetic fields, with the hope of linking their findings to other species with homing habits, including sea turtles, rainbow trout and bees. Although the project has its challenges, Keays believes that learning how nature detects magnetic fields could lead to the creation of artificial magnetoreceptors with the potential of treating human medical conditions, particularly relating to the brain.