Magnets: How Do They Work? Sea Turtle Edition

Sea turtles are absurdly awesome. One of world’s most ancient animals, sea turtles are thought to be over 100 million years old – dating back to the time dinosaurs roamed the Earth.¹ During their very long lives sea turtles can travel hundreds of thousands of miles, feeding and foraging over 8,000 miles away from their nests.² But, every breeding season they return home to the same stretch of beach that they were hatched on.

Credit: J. Roger Brothers

For fifty years, scientists have been befuddled by how turtles are able to return to their nest. And now we know. Sea turtles are even more awesome than we previously thought. While scientists have previously hypothesized that sea turtles use the Earth’s magnetic field to navigate their travels out at sea, a new study in Current Biology shows that their crazy homing ability is also derived from the magnetic field.³

The study, conducted by Brothers and Lohmann at the University of North Carolina, Chapel Hill provides compelling evidence that turtles somehow take a magnetic imprint of the beach they hatched on, and then use that magnetic imprint like a map to return to that same beach when it is their own turn to become parents.

Why sea turtles’ would want to return to the same beach is fairly clear: by returning to a safe location, with the necessary nesting environment, there is a better chance their hatchlings will grow up to be productive members of society. But the question is how do they do this? Brothers told the AAAS that while little is known about how animals detect the geomagnetic field, that it is most likely that tiny magnetic particles in the turtles’ brains respond to the magnetic field.

Credit: J. Roger Brothers

Brothers and Lohmann attacked the problem from a different direction. Instead of focusing on the biomechanics of magnetic imprinting, they hypothesized that if the sea turtles were able to discern the magnetic signature of their home, then perhaps there was some sort of disturbance in the force unique to that particular stretch of beach. And, that is exactly what the research found, “a strong association between the spatial distribution of turtle nests and subtle shifts in the Earth’s magnetic field.”⁴

So, even though we can’t figure out how turtles are able to imprint that magnetic signature, it’s pretty clear that they know it when they…feel?…it.

See. Told you. Turtles are freakin’ awesome. And so are fuckin’ magnets. Even when you do know how they work.