Wildlife Wednesdays: Earth's Magnetic Field and Sharks

Researchers confirmed, after long-held speculation, that sharks use the Earth's magnetic field as a natural GPS to help them travel miles across the world's oceans. Sharks are not the only creatures to have a natural GPS, sea turtles navigate the oceans too using earth's magnetic field. 

The study, published in the journal Current Biology, also answers why sharks can travel long distances and be able to find their way back to eat, breed, and give birth. "We know that sharks can respond to magnetic fields. We didn't know that they detected it to use as an aid in navigation. You have sharks that can travel 20,000 kilometers (12,427 miles) and end up in the same spot," says marine policy specialist Bryan Keller. 

Scientists based at Florida State University decided to study bonnethead sharks, a type of hammerhead. The study goes onto mention, "researchers exposed 20 bonnetheads to magnetic conditions that simulated locations hundreds of kilometers (miles) away from where they were caught off Florida. The scientists found that the sharks began to swim north when the magnetic cues made them think they were south of where they should be." Further study is needed to find how the sharks use the magnetic field to determine their location and whether other long distance swimming sharks use this same natural GPS. 

Keller said the study could help inform management of shark species, which are in decline. A study this year found that worldwide abundance of oceanic sharks and rays dropped more than 70% between 1970 and 2018.