Photo Courtesy of Smithsonian Ocean
My name is Talia Waxman, the newest columnist for The Fieldston News. This column is called “Did You Know?”, and with it I intend to highlight quirky and niche developments that the Fieldston community might not otherwise be aware of but would be interested in. This would include developments in science, cultural stories, profiles of people who have made significant contributions to their community but are not widely known and political developments in countries or areas of the world that do not get much attention.
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Did you know that sea turtles are able to find their way back to the same beach every year to lay eggs, even after swimming thousands and thousands of miles away?
Some scientists hypothesize that sea turtles use the earth’s magnetic field as an internal compass to find their nesting and breeding areas. This ability to use the earth’s magnetic field as a GPS of sorts is not found in younger turtles. Rather, this evolutionary mechanism is a skill of older adult sea turtles and is essential to their survival as a species. Older turtles can sense nearly undetectable changes in the Earth’s magnetic field to make their way back home.
Marine biologists Kenneth and Catherine Lohman carried out a study to test this hypothesis. Their experiment involved a circular pool surrounded by a large cube-shaped magnetic coil system. The magnetic coil could imitate the same magnetic pull the Earth’s magnetic field has on sea turtles. Lohman brought green sea turtles from a coastal feeding ground into the pool.
The marine biologists altered the magnetic field and observed how the sea turtles modified their swimming patterns. For example, if the magnetic coil had a charge similar to that 209 miles north of their home, they would swim to the south and vice versa.
This study suggests that sea turtles are able to detect a minor change in the Earth’s magnetic field. We don’t yet understand precisely how sea turtles are capable of such detection – a superhuman (or superturtle?) feat. As our own animal behavioral specialist, Howard Waldman said “It’s not surprising at all that sea turtles would use magnetic fields for navigation, as they are underwater and can’t make great use of the night sky to navigate and travel for hundreds of miles. But it’s also not surprising because so many animals, from snails to naked mole rats to many species of birds, also use the Earth’s magnetic fields to orient themselves and navigate. Not surprising, but so so cool! Evolution by natural selection provides many wonderful adaptations for life on Earth.”
The Lohman study was important to demonstrate how sea turtle migration will be impacted by human activity and climate change. If the turtle’s regular beach is destroyed or made inhospitable to turtle breeding, it is not clear that the turtle will make it to another beach to lay eggs. Until we can imitate different magnetic fields to encourage these sea turtles to nest at different homes, it is critical that we protect and preserve the homes to which they are accustomed.
