Sharks Use the Earth’s Magnetic Field Like A Compass

“It’s a really interesting and clear demonstration that sharks use the Earth’s magnetic field as a kind of map,” says Kenneth Lohmann, a biology professor at the University of North Carolina who was not involved in the study. Lohmann has documented similar abilities in salmon and sea turtles. He says this study suggests that the ability to navigate with magnetic sensitivity may be widespread among marine animals that migrate seasonally.

“It’s a bit like a child who’s learned their home address,” Lohmann says. When small, sharks learn the magnetic “address” of their native estuary or bay. This information will help them get back on track, even after traveling thousands of miles. (They may not have responded to magnetic information from Tennessee, I suppose, because it’s outside the area they know.)

Sperfumes use almon, in addition to magnetic data, to detect their places of reproduction, and sharks can do the same, especially at the end of their travels. “For a fine-scale movement, I think smell plays an important role,” Keller says, but he doesn’t think it’s powerful enough to guide him hundreds of miles.

Yet exactly how any animal hearing magnetic fields remains “a real mystery,” says Lohmann. One theory is that they have magnetite crystals, who feel the true north, embedded somewhere in their brain or nervous system. Another is that magnetic fields affect the receptors in their cells visual systems, overlapping colors or light patterns on his vision, such as an augmented reality headset. Perhaps the north appears as a red dye, and an animal follows only that color.

Sharks also have pores in their noses filled with Lorenzini ampoules, receptors that detect electric currents in the water; sharks find prey by electrically sensing the heartbeat. Perhaps these receptors also sense magnetic fields, or take them back indirectly by noticing how they interact with electric currents. No one can even make definitive claims. And, says Lohmann, “there is no reason to think that there is only one mechanism that all animals use.”

Studies like Keller’s are important because they help fill a piece of a long-standing puzzle about how sharks succeed in their vast migration, and give humans a better understanding of how our marine technologies affect them. “It has really big implications for the management and conservation of these species,” says Kyle Newton, a biologist at the University of Washington in St. Louis, who studies how races navigate with magnetic fields.

It’s something that’s particularly important to understand as offshore wind farms become more popular — and could disrupt these fields. Turbines transform energy from wind into energy that is conducted back to earth by means of cables underwater. And as the Keller cube used energy to mimic the Earth’s magnetic field, underwater power cables also create their own small magnetic fields in the ocean. These anomalies can confuse the animals, encouraging them to swim off the right path or attracting them to feed in an environment that does not have the right prey.

It is also unclear whether any interruptions actually occurred; These anomalies are small and may not have had any effect, Newton says. Or they may disturb some animals more than others. But we feel that people need to study the possibility so that we don’t end up experiencing these important migrations. Since Newton, since people can’t hear magnetic signals, “it’s easy for us to overlook this stuff. It’s not just on our radar. ”But if we understand the stimuli that other animals can feel, we can be careful not to do lasting damage to those indications.

Update 5-10-2021 13:18 PM: This story has been updated to correct the name of Kyle Newton’s university.

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