Sharks are guided by the magnetic field

How can you guide yourself in the sea when you are a shark? The key is instinct … and a particular compass. Sharks are guided by the magnetic field. Is it an acquired or an innate behavior? A team of biologists from Florida State University determines this. The results are in Current biology.

Sharks are guided by the earth's magnetic field.
Sharks are guided by the earth’s magnetic field.
Well-oriented traveler

It all started in 2005. A great white shark was chased from South Africa to Australia. He did it in a straight line, back and forth. He showed great precision in localizing. As if they had a compass and a map to guide them in the middle of the ocean. How did you do that?

A team of researchers led by Bryan Keller, an ecologist at Florida State University, looked into this. They did tests in a kind of controlled pool. Using the wiring, they simulated a custom magnetic field in the center of the pool. They placed 20 juvenile Florida shovelheads.

By creating a false magnetic “north”, the sharks swam there. They interpreted it as the way back home. In these cases, they were anchored in one of the walls of the pool that they wanted to get out of. Yes, sharks are guided by the magnetic field.

“We don’t know if it’s instinctive,” says Keller. With salmon and sea turtles it is. The animals analyzed had no “external experience” about what the birds should do, they seem to have been learned. Adults orientate themselves magnetically, but inexperienced youngsters do not. ‘

Back to the origin

Although the researchers used spade sharks for their experiments, Keller believes other species, such as the great white shark, which made long migrations, might have this ability as well. Now that the main question has been answered, the researchers now need to figure out how to do it.

‘The magnetic differences between geographic locations coincided with the genetic divergence of populations. We find evidence of this in both DNAs, “he says. Female sharks that return near where they were born to reproduce most likely use magnetic signals to determine where they are left. Clear biogeographical evidence that sharks are magnetic Use signals to guide yourself.

Are they using the magnetite contained in some of their cells? Or a photoreceptor protein from your retina? The answers to these questions are described in another chapter on the fascinating world of sharks.

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