For young loggerhead sea turtles, the allure of a squid is comparable to a shining disco ball. These creatures exhibit an enthusiastic “dance” when they detect food or even sense its proximity. They point their heads upward, open their mouths, and vigorously flap their front flippers in a motion similar to a dog paddling. Occasionally, they might even spin around on the spot.

A team of researchers recently utilized this unique behavior to investigate whether loggerheads can recognize the magnetic signatures of places where they have previously found food. Their findings, shared in Nature on Wednesday, indicate that these lively turtles exhibit their dance-like movements in response to magnetic conditions linked to food sources.

Kayla Goforth, the study’s lead author and a marine biologist at Texas A&M University, explains that the research demonstrates loggerhead sea turtles’ ability to learn and remember the magnetic signatures of specific locations. This capability allows them to construct a mental map of magnetic markers, functioning similarly to a GPS, she notes.

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Loggerhead turtles, along with other sea turtle species, are famous for their vast migratory journeys, spanning thousands of miles without losing their bearings. These turtles often return to the same feeding areas annually, and females typically lay eggs on the very beaches where they were hatched.

For decades, scientists have known that sea turtles use the Earth’s magnetic field as a navigational tool, similar to an internal compass. However, returning to a precise location requires more than just directionality; it requires knowing the exact magnetic coordinates. This has led some researchers to propose that sea turtles are capable of memorizing these specific coordinates for both feeding sites and nesting beaches.

To test this theory, Goforth and her team collected several loggerhead hatchlings from an island off the coast of North Carolina. These turtles were later returned to the wild. In laboratory conditions, the turtles were placed in containers surrounded by a magnetic coil system that generated varying magnetic fields corresponding to different geographic locations along the Eastern Seaboard, such as areas in the Gulf of Mexico or near Maine.

Each turtle was exposed to two different magnetic fields during a two-month conditioning period. They spent equal time in both fields but were only fed in one. Subsequently, during several days of trials, the researchers recreated these magnetic conditions but did not provide food.

The researchers discovered that the loggerheads exhibited their distinctive dance in response to the magnetic fields associated with previous feeding locations, even without actual food being present. This supports the idea that these animals are capable of learning and recalling the magnetic coordinates of key foraging spots, a skill similarly observed in salmon during their oceanic journeys.

Further tests conducted months later without reintroducing the turtles to those magnetic fields showed that the loggerheads still responded to the magnetic conditions linked to food. Goforth suggests that these turtles likely retain the magnetic coordinates for many years, perhaps even decades. “In the wild, they maintain feeding information from their hatchling stage all the way to adulthood, which spans about 20 years,” she remarks.

Marine biologist Jeanette Wyneken, from Florida Atlantic University and not involved in the study, emphasizes the importance of this geomagnetic memory for young sea turtles. Growing quickly to outsize predators is vital, she explains, and efficiently locating food is crucial for their development and survival.

Goforth and her team also explored whether the turtles’ ability to map magnetic locations was connected to their internal magnetic compass. They conducted similar experiments but introduced radiofrequency waves to disrupt the turtles’ magnetic orientation. The findings revealed that the turtles were still able to identify specific magnetic coordinates.

These results suggest that sea turtles have two separate systems for detecting magnetic fields. Previous studies have indicated that certain songbirds and newts also have dual magnetoreception systems. Given that birds and amphibians are distantly related to sea turtles, Goforth and her colleagues believe that magnetic compasses and maps might be common tools in the vertebrate navigation arsenal.