Scientists investigated a mystery of the sea. They found dancing turtles.
When a hatching sea turtle first pokes its head above the sand and scrambles to the sea, a watching child might ask how the turtle knows where to go and how girl turtles know to come back one day to a nearby beach to lay their eggs.
Even sea turtle scientists don't yet fully understand how the turtles use the sense of direction and navigation that helps them survive and return to nest on a beach near where they hatched. Two papers published this month, however, show researchers are getting closer to solving some of the questions that have puzzled them for years.
In one study, published Wednesday in the Science journal Nature, a crew of dancing loggerhead sea turtles revealed more about how they learn to use magnetic fields. Researching these skills more could one day offer humans clues to help improve our own navigation, said Kayla Goforth, a postdoctoral fellow at Texas A&M University and lead author of the study with seven research partners.
The other study, by a group of scientists at the University of Central Florida, shows young turtles may travel more deliberately to find food and safety than had been thought.
Animal magnetism
Many animals use magnetic sensing to find their way and to migrate, including birds, salamanders, butterflies and fish, said Goforth, who led the study while completing graduate work at the University of North Carolina. "It seems like we're constantly discovering more and more animals that have a magnetic sense. It's a widespread ability across the whole animal kingdom."
Goforth's research team found loggerhead turtle hatchlings can be conditioned to recognize magnetic fields, which allows them to return to the same feeding sites year after year or to the nesting site where they first emerged, she said.
No one had ever demonstrated whether turtles could learn magnetic fields, she said. In this study, hatchling loggerheads from a North Carolina beach were taken back to the laboratory and kept in aquarium tanks with separate magnetic fields replicating actual magnetic signatures in two ocean locations. They were conditioned by finding food in only one of the locations over two months.
The young turtles learned to distinguish the field where they found food, a gel mixture with fish flakes and nutrients, she said. They also received "an extra reward of squid and shrimp" when they returned to the location.
When they arrived in the spot where they expected to find food, the turtles would dance in anticipation, the study reported, tilting their bodies vertically, raising their heads near or above the water's surface, alternatively paddling with their flippers and sometimes spinning in place.
Not magic, but magnetic
The study demonstrates that magnetic fields may help the turtles "get back to the same feeding areas, just like we might return to our favorite pizza place again and again, but we learn a street address," Goforth said. The biologists used a magnetic coil system with an electric current running through it to re-create the magnetic fields the turtles associated with the food.
After the first experiment, Goforth said, researchers were amazed the turtles had learned to return to the same spot. After a second group of hatchlings demonstrated the same ability, the scientists were "really excited." The turtles even remembered the location four months later.
The experiment was the first to provide strong evidence that a sea turtle could learn to associate a magnetic field with food, she said. In the ocean, successful foraging may prompt a turtle to notice and remember the "signature" of a feeding area.
The young turtles, about the size of a dinner plate, were released into the sea about a year after they were collected.
The two-part study also exposed sea turtle hatchlings in Melbourne Beach, Florida, to radio frequency fields to determine how that might affect their magnetic senses. "We have eyes for visual sense and noses for smelling," Goforth said. "Turtles have a magnetic sense. We don't know what that structure is yet.
"Figuring that out, it's kind of the last sense that we know of right now that we don't understand," she said. If researchers can understand how animals can navigate with magnetic fields, "then we could possibly develop our own technology that uses magnetic fields for navigation as opposed to satellites."
Determined swimmers, not passive drifters
In the study off Florida's West Coast, researchers with the University of Central Florida's Marine Turtle Research Group tracked the movements of four species of wild-caught juvenile sea turtles by satellite signals from tiny GPS tags from 2011 to 2022. The resulting study, published in the journal Proceedings of the Royal Society B: Biological Sciences, showed young turtles are active swimmers during their early lives rather than passive drifters.
"We’ve had massive data gaps about the early baby to toddler life stages of sea turtles,” said Kate Mansfield, a marine scientist at the University and director of the turtle research group. “This part of their long lives has been largely a mystery.”
Researchers had thought juvenile sea turtles stayed far offshore, where it might be safer for them than closer in, where birds, sharks and big fish lurk. This study found that turtles were swimming back and forth between the shallower waters, approaching the shore then turning away to avoid it.
Understanding the movement patterns can help guide conservation efforts to protect crucial habitats for sea turtles, said Katrina Phillips, who led the study with Mansfield and Nathan Putman, an ecologist at LGl Ecological Research Associates in Texas. They compared the movement patterns of the turtles with passive drifting devices that were released with the turtles.
Historically, information about the young life stage of turtles was limited to sightings of opportunity − which can be challenging when trying to spot tiny hatchlings from passing boats, Mansfield said. The study showed that this stage of a turtle's life, which has been called "the lost years," is more complex than assumed.
Dinah Voyles Pulver covers climate change, wildlife and the environment for Paste BN. Reach her at dpulver@usatoday.com or @dinahvp on Bluesky or X.