Watch sea turtles dance for joy when they magnetically sense it’s snack time
The reptiles appear to remember specific magnetic characteristics of preferred feeding sites
If the promise of a tasty meal makes you want to jump for joy, you may relate to the loggerhead turtle. These animals have an uncontrollable urge to dance whenever they anticipate food—a trait scientists behind a study out today in Nature used to test whether the reptiles can memorize their favorite feeding sites based on Earth’s magnetic fields.
It’s well known that certain migratory animals, such as sea turtles and salmon, navigate using Earth’s magnetic field as a compass, but scientists weren’t sure whether they also learn and remember the “magnetic signatures” of specific locations based on their position within Earth’s magnetic field. To find out, a team of researchers put 62 loggerhead turtles (Caretta caretta) into bowls of water surrounded by electromagnets that could be tuned to create different magnetic conditions.
Each turtle spent time in a bowl tuned to a particular magnetic inclination and intensity—settings that are used to navigate by compass—and received scrumptious treats of nutrient gel and squid. When given their snack, the loggerheads performed what scientists refer to as the “turtle dance,” opening their mouths wide, splashing frantically, and lifting their bodies out of the water (seen above). After the turtles learned to associate the specific magnetic signature with a meal, the scientists turned on the electromagnets but withheld the treat. Nevertheless, the turtles still danced expectantly, suggesting they remembered the magnetic conditions associated with snack time. Even 4 months later, they shimmied whenever they felt that magnetic signature.
Next, the researchers tried blocking the turtles’ magnetic recognition by introducing radiofrequency fields known to impair some animals’ magnetic compass. Although this discombobulated the turtles during a navigation experiment, they still danced when they felt the food-related magnetic signatures. That implies the turtles possess separate biophysical mechanisms for navigation and magnetic memory. The same phenomenon has also been observed in certain birds and amphibians, the researchers note, suggesting many migrating vertebrates may have evolved two separate ways to navigate Earth’s magnetic field—to home in on breeding grounds, favorable climates, or just a delicious nosh.
