It’s one of the most miraculous journeys in the natural world: sea turtles travel thousands of miles across the ocean to return to the very beach where they first scuttled into the sea.
There aren’t exactly brightly lit mile markers in the sea, so how they do it? Scientists from the University of North Carolina (my alma mater!) say they have figured it out.
The researchers say that loggerhead sea turtles appear to be able to determine their longitude using the strength and angle of the Earth's magnetic field. Although several species of turtles are known to use magnetic cues to determine latitude, it had never been shown for longitude.
I didn’t realize this, but apparently the most difficult part of open-sea navigation is determining longitude (east-west position.) While human navigators struggled for centuries to figure it out on long-distance voyages, loggerhead hatchlings are naturals as soon as they hit the water.
To carry out the research loggerhead hatchlings were placed in circular water containers and tethered to electronic tracking systems to monitor their swimming direction.