Sharks use Earthâs magnetic field as a GPS, FSU researchers say The study focused on bonnetheads but probably applies to any species, such as great whites, making cross-ocean journeys, according to the scientists. Â Â Scientist Bryan Keller has conducted research on bonnethead sharks, like this one he found in September 2015 along the North Edisto River in South Carolina. [ AP ] Updated 49 minutes ago Sharks use the Earthâs magnetic field as a sort of natural GPS to navigate journeys that take them great distances across the worldâs oceans, scientists at Florida State University have found. Researchers said their marine laboratory experiments with a small species of shark confirm long-held speculation that sharks use magnetic fields as aids to navigation â behavior observed in other marine animals such as sea turtles.