FREE CONTENT: It’s a sea turtle mystery that has stumped scientists for decades: How does the female sea turtle, which travels across thousands of miles of open ocean each year, still manage to navigate back to the same beach where she hatched to lay her eggs? Keep in mind that there are no visual guideposts in the open ocean where sea turtles spend most of their lives. It is vast and featureless — an expanse of blue. And yet every two to three years, sea turtles dig their nests at the same location where they once crawled out of their own leathery eggs — a behavior known as natal homing. Scientists have hypothesized that sea turtles may rely on information in the Earth’s geomagnetic field to help them find their way back to their birth beach, but they had never been able to find any evidence to support this hypothesis. Until now. In a paper published Thursday in Current Biology, researchers show that subtle changes in the Earth’s magnetic field affect where loggerhead sea turtles bury their eggs on the Florida coast, providing the first clue that what’s known as the geomagnetic imprint hypothesis may be correct. Since the mid-1990s, scientists have known that sea turtles are capable of deriving navigational information from the Earth’s geomagnetic field — a field we humans cannot sense without the use of scientific instruments. The magnetic field around the Earth looks similar to the magnetic field around a bar magnet. Its intensity is strongest at the poles, and weakest at the equator. It also intersects the Earth at different angles which are known as inclination angles.
Posted on: Sat, 17 Jan 2015 02:00:17 +0000
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