For Sea Turtles, There’s No Place Like Home
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14 Apr For Sea Turtles, There’s No Place Like Home

Posted at 12:54h in Issue II Winter 2023 by

By Kylan Huang

Picture this: A newly hatched baby sea turtle digs its way out of its egg, fights the waves lapping onto the beach, and crawls into the ocean. The beach is pretty ordinary—you wouldn’t even remember it after a few days—but years later, this little turtle will find its way back and lay its own eggs on the very same beach.  

How in the world do these sea turtles find their way back home? It seems like a wild feat, considering humans have a hard time even remembering what they ate for dinner the previous night. Well, studies done on loggerhead sea turtles have shown that these turtles have their own memory superpower: geomagnetic imprinting.

Scientists have hypothesized that these turtles use the Earth’s magnetic field to find their way back home. Our planet’s magnetic field is like a magnet, with lines running from the Southern Hemisphere to the Northern Hemisphere (below and above the equator, respectively). The vertical ring-like shapes cover less distance around the magnetic equator, and they become larger around the poles. The shape of each “ring” can be predicted for different locations. Similar to how humans use latitude and longitude coordinates to navigate, turtles use this magnetic field. 

This explains the “geomagnetic” part. But what does “imprinting” mean?  Imprinting is a specific type of learning done over a short period of time with long-lasting results. It occurs when an animal needs to learn something that will be critically important for them in the future. For example, birds recognize the first thing they see as their mother, whether that’s you, a set of car keys, or even a math textbook, as one study found. Scientists believe that sea turtles, after being born, are able to learn the magnetic signature of the beach they were born on—essentially, the mixture of minerals in the beach’s soil that can be used to uniquely pinpoint the beach—and use those results to find their way home. 

One of the most fascinating cases of geomagnetic imprinting is green sea turtles navigating their way through the Indian Ocean. They often need to readjust their course to compensate for errors of hundreds of miles—but the turtles always arrive at their home beach. The magnetic field also experiences constant change, but scientists have noticed that even as the magnetic field of the Earth shifts, Florida turtles return to the shifted beach location. Incredible!