Researchers at the University of North Carolina at Chapel Hill have revealed that young loggerhead turtles use a touch-based magnetic sense to determine their position during long ocean migrations. By training hatchlings to associate specific magnetic fields with food and then disrupting their senses, the team confirmed this mechanism. The findings, published in the Journal of Experimental Biology, explain how these animals navigate thousands of kilometers from birth.
Loggerhead turtle hatchlings embark on epic journeys spanning thousands of kilometers shortly after hatching on beaches, relying on innate navigational tools to survive decades at sea. Scientists long suspected these young turtles possess a magnetic map for location and a compass for direction, but the exact sensing method remained unclear until now.
Animals detect Earth's magnetic fields through two primary ways: light-sensitive molecules that might allow visual perception of magnetic patterns, or magnetite crystals that enable a tactile feel of the forces. To test which loggerheads use for mapping, researchers led by Alayna Mackiewicz, Dana Lim, and colleagues at UNC Chapel Hill trained eight hatchlings over two months. They associated magnetic fields mimicking those near Turks and Caicos islands and Haiti with feeding, prompting the turtles to perform an excited "dance"—raising their bodies, opening mouths, and flapping front flippers.
"They are very food motivated and eager to dance when they think there is a possibility of being fed," Mackiewicz noted. After training, the team applied a strong magnetic pulse to temporarily disrupt the turtles' ability to feel magnetic forces. When re-exposed to the trained fields, the hatchlings danced significantly less, indicating reliance on this touch-based sense rather than visual detection.
This complements their magnetic compass, likely vision-based, for directional guidance. While other cues may assist, the tactile magnetic sense plays a central role in positioning. The study, detailed in the Journal of Experimental Biology (2025; 228 (22)), highlights the sophistication of these hatchlings' inherited navigation system.
The experiments underscore the turtles' behavioral responsiveness, with training requiring patience but yielding clear results on their sensory toolkit.