Several hypotheses and countless different studies are being considered, but the truth is that we still don't have an evidence-based answer to this question. A new article, published in the Philosophical Transactions of the Royal Society B journal, presents a novel approach to the subject, namely, it suggests that sensing a magnetic field may be the result of a symbiotic relationship between animals and a specific group of bacteria capable of orienting themselves along the lines of our planet's magnetic field. "The search for the mechanism behind this is one of the last big frontiers in sensory biology, and is often described as looking for a needle in a haystack," explains Robert Fitak of the University of Central Florida, co-author of the new study.
For decades, scientists have been aware that a number of organisms, bees, birds, whales and eels, have the ability to sense the Earth's magnetic field, this is called magnetoreception and is used by some organisms for navigation, but the exact mechanisms of its action still remain for us a secret. In recent years, however, a trend has emerged that studies the aforementioned theory of the symbiotic relationship with bacteria, hence the latest article in which the authors also present concrete evidence. In their opinion, these are magnetotactic bacteria, i.e. those that orient themselves along the magnetic field with the help of specialized intracellular organelles called magnetosomes.
We have already seen several similar studies, but none have yielded actual evidence of traces of these bacteria in animal tissue - but this time is different as the authors point to a large metagenomic database that shows that genetic traces of magnetotactic bacteria can be found in many animal species . "The presence of these magnetotactic bacteria has been overlooked or lost in the mass scale of these databases," Fitak suggests. In his opinion, if we delve into this data, we will find evidence that the bacteria in question are present in many species of animals suspected of having magnetic field sensing capabilities, such as North Atlantic right whale, loggerhead turtle and mouse-eared nightcap.
Robert Fitak also says that he is currently working with his colleagues and local researchers at the University of Central Florida to create a genetic test for these bacteria, and plans to test many animals with them, such as turtles, fish, lobsters and birds, to prove the validity of his theory. And while we are still speculating to this point, the team believes the hypothesis is based on strong evidence and that it is worth spending more time on it, as there are still some puzzles to unravel: - Even if the symbiotic magnetic sense is widespread, before further challenges in discovering the mechanism by which bacteria and the host's organism communicate, ie how the host, that is, for example, birds, sense the bacterial response to changes in the magnetic field.