[Curiosities] Terrestrial magnetism, the GPS of sharks

[Draeno]

 

Since its in-depth study began in the 1970s, sharks around the world have seen their po[CENSORED]tions decline by up to 71%. That is why understanding any aspect of shark biology is essential for their conservation.

In this sense, sharks, in addition to other species of the elasmobranch group such as rays, are some of the animals that carry out the longest migrations in the world. These are highly mobile species whose habitats can span thousands of kilometres. They are also characterized by their great fidelity to the place they came from and by the fact that throughout their lives they return on various occasions to specific breeding or feeding places, a feat that becomes all the more incredible when we take into account that their world , the vast ocean, is a three-dimensional universe, uniform and devoid of physical borders or landmarks that can serve as a reference for the orientation of these animals.

However, when we think about sharks and their way of understanding the world, we cannot do it in the same terms as with respect to other animals. And it is that despite having a powerful sense of smell and acute hearing, when it comes to orienting themselves in the ocean, sharks have developed, in the same way as birds, an exclusive navigation system in which they use magnetic fields terrestrial.

In fact, researchers have known for a long time that elasmobranchs are sensitive to electromagnetic fields, so the possibility that sharks used their electrosensory organs to somehow obtain information from the Earth's magnetic field for navigational purposes, is not. it was something new.

However, despite the probability of the hypothesis, scientists have never been able to demonstrate the mechanisms underlying this ability. This, however, changed in the year 2021, when the team of researchers led by Florida State University marine policy expert, Bryan Keller, decided to study the behavior of a group of head sharks in the face of terrestrial magnetic fields. de shovel -Sphyrna tiburo- a species of hammerhead shark that can be found in the waters of the two margins of the American continent, and that every year returns to the same studies after its migration.

To do this, they captured 20 specimens of the species, and by using Merritt coils they exposed the animals to magnetic conditions that represent places hundreds of kilometers away from their place of capture. With this, using induced magnetic fields, scientists were able to demonstrate that sharks were capable of interpreting terrestrial magnetism and orienting themselves based on it. For example, sharks started swimming north when magnetic cues made them think they were south of where they should be.

Thus, the results of the study, published in the journal Current Biology under the title Map-like use of Earth's magnetic field in sharks, show that the terrestrial geomagnetic field provides sharks with information that can function as both a map and a compass. . The map would allow the animals to obtain spatial information relative to their location, while the compass allows them to maintain a directed course, and together, these facilitate successful shark migrations: a finding with profound implications for the conservation of numerous shark species. and rays, since it will allow scientists to predict their location and behavior much more accurately throughout the year.

 

https://www.nationalgeographic.com.es/mundo-animal/magnetismo-terrestre-el-gps-de-los-tiburones_19321