Sharks use the Earth’s magnetic field as GPS, according to the Science & Tech News study
Scientists have discovered that sharks use the Earth’s magnetic field as a type of natural GPS to control long journeys across the world’s oceans.
Marine laboratory experiments with a small species of shark have confirmed longstanding suspicions that sharks use magnetic fields to aid navigation.
This behavior has also been observed in other marine animals, including sea turtles.
The study, published in the journal Current Biology, also reveals why sharks are able to cross seas and find their way back to feed, breed and give birth, according to market policy specialist Bryan Keller, one of the authors of the study.
He said, “We know that sharks can react to magnetic fields. We didn’t know they recognized it as a navigational aid … They have sharks that can travel 20,000 km and land in the same place.”
Researchers were intrigued by how sharks have been able to do long-distance migrations for years.
The sharks make their journeys in the open ocean where they encounter few physical features such as coral that can serve as landmarks.
In search of answers, scientists at Florida State University decided to study crested sharks – a type of hammerhead that lives on both American coasts and returns to the same estuaries every year.
They exposed 20 hood heads to magnetic conditions that simulated locations hundreds of miles from where they were captured off Florida.
The researchers found that the sharks began swimming north when the magnetic signals led them to believe they were south of where they were supposed to be.
Robert Hueter, retired senior scientist at Mote Marine Laboratory and Aquarium who was not involved in the study, described the results as compelling.
However, he said more study is needed to find out how the sharks use the magnetic fields to determine their location and whether larger, far-flung migratory sharks use a similar system to find their way.
He said, “The question has always been, even if sharks are sensitive to magnetic orientation, do they use that sense to navigate the oceans, and how? These authors have made some progress in eliminating this question.”
The dependence of the hood’s head on the earth’s magnetic field is likely shared by other shark species, such as B. Whites who travel across the ocean, researchers say.