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Geomagnetic Imprinting on Sea Turtles

Last summer I was told that sea turtles could travel thousands of kilometres using the Earth’s magnetic field back to the beaches where they hatched, in order to reproduce themselves. But, how exactly do sea turtles do that? Turns out, when they hatch, the specific magnetic field of the beach where they were born becomes imprinted in their brain. As they mature, every year they return to those beaches and lay their eggs.

That is the theory behind this extraordinary observation. However, it does not always work out. You may wonder, what happens when there is another beach with a very similar magnetic field? The sea turtles can sometimes lay eggs in those beaches too, scientists found out when they observed the genetics of different sea turtles. For example, they found that loggerheads have laid eggs in beaches that are very far away from their original beach. However, one similarity between those beaches is that they have a similar magnetic field. This has explained a lot of the patterns shown by marine animals especially sea turtles.

In addition, we can conclude that sea turtles can detect the intensity and the inclination of the magnetic field lines across the globe. Magnetic field lines are perpendicular to the Earth’s surface at the poles. As the lines stretch towards the opposite pole, they intersect with the surface in different ways. For example, at the equator, the magnetic field lines are parallel to the surface.

Furthermore, apart from teaching us more about these marine creatures, these studies can also help us improve the way we conserve them. For example, a very important point I was told last summer was that humans have to avoid building strong magnetic structures close to the beaches. These structures, such as power lines and large beachfront buildings, can confuse the sea turtles and cause a drastic change in migration patterns. A key part to conservation is understanding the fascinating behaviour of the animals we are trying to protect it.

Laura L, Year 12

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