New Evidence Suggests Sharks Use Earth's Magnetic Field to Navigate
Bonnethead sharks swam in the direction of their home waters when placed in a tank charged with an electromagnetic field
Great white sharks travel hundreds of miles to specific locations in the world’s oceans. (Reinhard Dirscherl / ullstein bild via Getty Images)
By Alex Fox
SMITHSONIANMAG.COM
MAY 6, 2021 11:00AM
New Evidence Suggests Sharks Use Earth’s Magnetic Field to Navigate
Bonnethead sharks swam in the direction of their home waters when placed in a tank charged with an electromagnetic field
Great White Shark
Great white sharks travel hundreds of miles to specific locations in the world’s oceans. (Reinhard Dirscherl / ullstein bild via Getty Images)
By Alex Fox
SMITHSONIANMAG.COM
MAY 6, 2021 11:00AM
4138
Every December, great white sharks swimming off the coast of California make a beeline for a mysterious spot in the middle of the Pacific roughly halfway to the Hawaiian islands. The sharks travel roughly 1,000 miles to the so-called white shark cafe. Tracking data has revealed that their routes are remarkably direct considering their paths traverse apparently featureless open ocean. Tiger sharks, salmon sharks and multiple species of hammerheads also make lengthy journeys to and from precise locations year after year.
Pete Klimley, a retired shark researcher who worked at the University of California, Davis calls the ability of some animals to find their way to pinpoint locations across the globe “one of the great mysteries of the animal kingdom.”
Now, new research published today in the journal Current Biology provides new support for a longstanding hypothesis that sharks use the Earth’s magnetic field to navigate during their long-distance migrations. Scientists caught bonnethead sharks off the coast of Florida and put them in a tank surrounded by copper wires that simulated the magnetic fields sharks would experience in locations hundreds of miles from their home waters. In one key test, the bonnetheads were tricked into thinking they were south of their usual haunts and in response the sharks swam north.
Iron and other metals in Earth’s molten core produce electrical currents, which create a magnetic field that encircles the planet. The north and south poles have opposing magnetic signatures and invisible lines of magnetism arc between them. The idea that sharks can navigate by sensing these fields rests on the fact that Earth’s geomagnetism isn’t evenly distributed. For example, the planet’s magnetism is strongest near the poles. If sharks can somehow detect the subtle perturbations of Earth’s magnetic field, then they might be able to figure out which way they’re heading and even their position.
More:
https://www.smithsonianmag.com/science-nature/new-evidence-suggests-sharks-use-earths-magnetic-field-navigate-180977668/
= new reply since forum marked as read
