Many animals – birds, sea turtles, lobsters, moths, whales and other bats – “are capable of detecting ripples in the Earth’s magnetic field…observe National Geographic.
Relying on a mysterious biological compass, “these animals use invisible magnetic landmarks, emanating from the depths of the Earth, to orient themselves on the surface and accomplish incredible migrations, both across the sky and the oceansâ€adds the magazine. “But exactly how these animals perceive the planet’s magnetic pull has remained, for decades, one of the greatest mysteries of biology….
In fact, the subject of sensors of the earth’s magnetic field in animals has given rise to numerous hypotheses, and some studies locate the biological compass of pigeons in their ears. We also know that the beak, and especially the eyes – knowing that birds orient themselves primarily thanks to the sun – are decisive in orientation.
Macrophages
A team of German scientists proposes another hypothesis: according to their study, published on May 28 in the journal Sciencethe internal compass of homing pigeons, the objects of this research, would ultimately be located in the cells of their liver.
To reach this conclusion, the researchers looked at macrophages, cells belonging to the immune system, very rich in iron. It is this concentration of iron which would help the pigeons to “detect magnetic fields and transmit this information to the brainâ€according to Ars Technica.
To get to the bottom of it, scientists “gave half of a group of 34 homing pigeons a treatment intended to eliminate macrophagesâ€explain ScienceNews.
And when the sky was overcast – “It was crucial that the birds had absolutely no idea of the position of the sunâ€underlines Christian Kurts, one of the authors of the study – they have “transporté les pigeons à 19 kilomètres de là et les ont relâchés, équipés de balises GPSâ€.
Pigeons égarés
The birds whose macrophages had not been eliminated returned to their dovecote in approximately 70 minutes. And those deprived of macrophages “flew in all directions and didn’t return home until the next dayâ€when the sky was clear and the sun was visible again, reports the site.
If these results seem convincing, many questions remain, observes Susanne Ã…kesson, animal ecologist at Lund University (Sweden), not involved in this work. “We now need to determine how these [cellules] transmit information to the nervous system and which areas of the brain are used…
It will also remain to be established whether other birds, bats, sharks and other animals with a magnetic sense also have these white blood cells in their liver.
Furthermore, despite the results obtained, the subject remains controversial and “There will certainly be skepticsâ€estimates neurologist John Phillips, of the Virginia Tech Institute in Blacksburg, who did not participate in the study. “However, the scientific rigor of this work is such… that even the most skeptical “one will be able to ignore themâ€he declares.
