In the vast, featureless expanse of the open ocean, how does a sea turtle find its way? For loggerhead turtles, the answer lies in an invisible force: Earth’s magnetic field. But these ancient mariners don’t just use magnetism as a compass — they also create a mental map of the world, memorizing the unique magnetic signatures of where they hatched or places where they’ve found food.
And how do scientists know this, you may ask? Because the turtles dance.
When baby loggerheads sense food, they erupt into a joyful display of head bobs, flipper flaps, and twirls. So, researchers have dubbed the behavior the “turtle dance.” This exuberant routine isn’t just absolutely adorable; it’s also a window into the turtles’ remarkable ability to navigate using Earth’s magnetic field. A new study, published in Nature, reveals that loggerheads can learn and remember the magnetic signatures of specific locations, a skill that helps them survive in the wild.
“They’re essentially creating a magnetic map,” says Kayla Goforth, a marine biologist at Texas A&M University and lead author of the study. “It’s like they have a built-in GPS.”
The Map Behind the Dance
Loggerhead sea turtles are born with an innate ability to detect Earth’s magnetic field, which they use as a compass to guide their migrations. Somehow, they can travel across thousands of miles of ocean and then return to the very same beach where they hatched to lay their eggs. Scientists have long wondered if they could also use magnetism to pinpoint specific locations, such as feeding grounds or nesting beaches.
“They returned to approximately the same beach 20 years after they were born there,” Goforth said.
To find out, Goforth and her team turned to the turtle dance.
The researchers collected loggerhead hatchlings from a beach in North Carolina and brought them to the lab. There, the turtles were placed in buckets equipped with magnetic coil systems. By running electric currents through the coils, the team could recreate the magnetic fields of different locations, such as the Gulf of Mexico or the coast of Maine.
Each turtle was exposed to two magnetic fields but only fed in one. After two months of conditioning, the turtles began to dance whenever they encountered the magnetic field associated with food — even when no food was present. They get really excited. Some turtles flap their flippers vigorously, while others just stick their heads out of the water. It’s like they’re saying, “Hey, I remember this place! Where’s my snack?”
The team repeated the experiment with different pairs of magnetic fields, gradually testing the turtles’ ability to distinguish between increasingly similar signatures. Remarkably, the turtles could tell the difference between magnetic fields just 100 kilometers apart — a feat akin to recognizing the subtle differences between two neighboring towns.
A Dual Magnetic Sense
The study also revealed that loggerheads have not one, but two distinct ways of detecting magnetic fields. The first, a compass sense, helps them orient themselves in a particular direction. The second, a map sense, allows them to recognize specific locations.
To test this, the researchers added radiofrequency waves to disrupt the turtles’ compass sense. Even without their internal compass, the turtles could still recognize the magnetic signatures associated with food. This suggests that the map sense operates independently, possibly using a different mechanism.
It’s like having two separate tools in your navigation toolbox. One tells you where you are, and the other tells you which way to go.
“That was really exciting, because we don’t have a very good idea of the sensitivity of the turtle’s map sense,” Goforth told Defector.
This dual system isn’t unique to turtles. Similar abilities have been observed in salmon, birds, and even newts, hinting that magnetic navigation might be a widespread trait among vertebrates.
Why It Matters
For loggerhead turtles, the ability to remember magnetic coordinates is a matter of survival. Juvenile turtles spend years drifting in ocean currents, growing large enough to evade predators. Finding food quickly is crucial, and their magnetic map helps them return to productive feeding grounds.
The findings also shed light on the broader mysteries of animal navigation. Despite decades of research, scientists still don’t fully understand how animals perceive magnetic fields. The new study suggests that turtles might rely on multiple mechanisms, opening up new avenues for exploration.
“This is a new way of thinking about how turtles use the magnetic field to navigate,” Katrina Phillips, a biologist at the University of Massachusetts Amherst, told New Scientist. “It’s fascinating because we still don’t know how they’re perceiving it. This research is getting at the heart of that question.”
In the face of an ever-changing ocean, these ancient creatures have evolved a remarkable system to find their way. And sometimes, they celebrate with a little dance.
When you see it, you can’t help but smile.
