Scientists say that sharks use the Earth’s magnetic field like the Global Positioning System (GPS)


Scientists have discovered that sharks use Earth’s magnetic field as a kind of natural global positioning system (GPS) to travel long distances across the world’s oceans.

The researchers said their marine laboratory experiments with small species of sharks confirm long-standing speculation that sharks are using magnetic fields as aids for navigation – a behavior seen in other marine animals such as sea turtles.

Their study, published this month in the journal Current biologyIt also explains why sharks are able to cross seas and find their way to feed, reproduce and give birth, says marine policy researcher Brian Keeler, one of the study’s authors.

“We know that sharks can respond to magnetic fields,” Keeler said. “We didn’t know they discovered it as a navigation aid … You have sharks that can travel 20,000 kilometers (12,427 miles) and end up in the same place.”

The question of how sharks perform long-distance migrations has puzzled researchers for years. Sharks make their journeys in the deep sea as they encounter little physical features such as coral reefs that can serve as landmarks.

In search of answers, scientists at Florida State University set out to study hammerhead sharks – a type of hammerhead shark that lives off the coast of America and returns to the same estuaries every year.

Researchers exposed 20 bone heads to magnetic conditions mimicking locations hundreds of kilometers from where they were captured off Florida. Scientists found that sharks began swimming north when magnetic signals made them think they were located south of where they should be.

This finding is compelling, said Robert Otter, emeritus chief scientist at the Mote Marine Laboratory & Aquarium, who was not involved in the study.

Huetter said more study is needed to find out how sharks use magnetic fields to determine their location and whether large migratory sharks over long distances use a similar system to find their way.

The question has always been: Although sharks are sensitive to magnetic orientation, do they use this meaning to navigate the oceans, and how? And these writers have made progress in solving this problem.

Keeler said the study could help inform the management of shark species that are in decline. a study This year it was found that the global abundance of sharks and ocean rays decreased by more than 70% between 1970 and 2018.

The researchers say the Bonnethead’s dependence on Earth’s magnetic field is likely shared by other species of sharks, such as large eggs, that make trips across the oceans. It is very unlikely that hat heads developed a magnetic sensitivity and that other nomadic sharks did not, Keeler said.


Follow Patrick Whittle on Twitter: @ pxwhittle


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