Because sharks travel thousands of miles each year between the same locations, they likely use the Earth’s magnetic field to navigate their habitat waters.
That’s what the researchers say they found after studying the head sharks – which could provide a glimpse into how great white sharks navigate between distant locations, returning to the exact same location every year.
“This research is exciting,” said Brian Keeler, principal investigator at Florida State University’s Coastal and Marine Laboratory.
“It shows how these animals maintain navigational success even as they travel thousands and thousands of miles,” he said.
Keeler cited previous research on great white sharks traveling from the tip of South Africa all the way to Australia and back – about 12,500 miles back and forth.
“They went back to the same location, and they didn’t have a cell phone or garmin to lead the way,” Keeler said, adding that the researchers were interested in whether the sharks were using the Earth’s magnetic field while they traveled these far distances.
For the study, researchers captured 20 young heads off the coast of Florida in the Gulf of Mexico. These sharks return to the same estuaries on a seasonal basis.
Sharks were transported from the Gulf of Mexico to Florida State University’s Coastal and Marine Laboratory, where researchers used “magnetic displacement” to expose them to magnetic conditions that represent locations hundreds of kilometers away from their capture site.
Manipulation of local magnetic fields was achieved by using merit coils aligned on the reservoir in such a way that the sharks would think they were elsewhere.
“When they were exposed to a field that was a site 600 kilometers south of their home, they turned north to their home,” Keeler said.
“The exciting thing is when displacement, they are heading towards the targeted sites … heading towards home,” he said.
The research focused on long-range shark moves. Going forward, researchers are interested to see if sharks are using Earth’s magnetic field for everyday movements as well.