Researchers are working out how sharks use the Earth’s magnetic field to guide their international adventures. 

Researchers have previously established that some species of sharks travel over long distances to reach very specific locations year after year. 

They also knew that sharks are sensitive to electromagnetic fields. As a result, scientists had long speculated that sharks were using magnetic fields to navigate. 

However, until now, no one had worked out how to test this in sharks.

The researchers used magnetic displacement experiments to test 20 juvenile, wild-caught bonnethead sharks. 

In their studies, they exposed sharks to magnetic conditions representing locations hundreds of kilometres away from where the sharks were actually caught. Such studies allow for straightforward predictions about how the sharks should subsequently orient themselves if they were indeed relying on magnetic cues.

If sharks derive positional information from the geomagnetic field, the researchers predicted northward orientation in the southern magnetic field and southward orientation in the northern magnetic field, as the sharks attempted to compensate for their perceived displacement. 

They predicted no orientation preference when sharks were exposed to the magnetic field that matched their capture site. 

It turned out, the sharks acted as they had predicted when exposed to fields within their natural range.

“How cool is it that a shark can swim 20,000 kilometers round trip in a three-dimensional ocean and get back to the same site?” asked Bryan Keller of Florida State University Coastal and Marine Laboratory. 

“It really is mind blowing. In a world where people use GPS to navigate almost everywhere, this ability is truly remarkable.

“This research supports the theory that they use the earth's magnetic field to help them find their way; it's nature's GPS.”