The **loggerhead sea turtle** (or caguama) uses the **Earth’s magnetic field** to create a personal map of its favorite places. Research once again demonstrates the incredible ability of migratory animals to orient themselves.
Some species that travel long distances across the globe, such as **birds, salmon, lobsters, and sea turtles**, are known to navigate using the lines of the Earth’s magnetic field that run from the North Pole to the South Pole.
Scientists knew that animals used this **magnetic information** as a compass to determine their location.
Now, these new findings suggest that sea turtles, like the loggerhead or caguama (Caretta Caretta), known in all the planet’s oceans, are also capable of mapping out a complete **magnetic map**, with their favorite places for **nesting** or feeding.
This implies that migratory animals “learn the magnetic coordinates of the destination,” **similar to a GPS**, according to a study in the journal Nature led by Kayla Goforth, from the University of North Carolina.
The research provides the first “direct evidence that an animal can learn and remember the **natural magnetic coordinates** of a geographic area.”
The mystery of magnetoreception
Exactly how they achieve this remains a mystery. Researchers found that the turtles’ ability to create maps was **independent of their internal compass**. This suggests that the two forms of “magnetoreception” work differently.
For the experiment, scientists placed young loggerhead sea turtles in a tank surrounded by a **magnetic coil** that replicated the magnetic field of the Atlantic Ocean.
For two months, the scientists daily changed the tank’s magnetic field, replicating the conditions between the coasts of the United States and the Gulf of Mexico.
However, the turtles were only fed when they received the **magnetic information** from one of the areas.
The dance of the loggerhead sea turtle
When the turtles anticipated that there was food, they would flap their flippers, open their mouths, and swim in circles in the water.
The researchers filmed this behavior, which they called the **”loggerhead dance”**.
The turtles danced more enthusiastically in the tank where they knew there would be food, “clear evidence” that the turtles can learn the magnetic signatures of **”specific geographic areas”**, the researchers stated.
Even four months later, when tested again, the turtles still knew where they should dance.
No one knows exactly how animals tune into this magnetic information.
One theory is that some can **detect the influence of the magnetic field** when a chemical reaction occurs between molecules sensitive to light.
But when researchers tried to interfere with this process using what is called **radiofrequency fields**, the turtles continued dancing in place without altering their behavior.
A separate experiment that tested the turtles’ internal compasses was more enlightening.
In a tank replicating the **magnetic conditions of the archipelago** of Cape Verde, in West Africa, radiofrequency emissions seemed to disorient the turtles’ compasses, sending them in random directions.
The researchers concluded that “a reasonable working hypothesis is that the sense of the compass depends on chemical magnetoreception, while the sense of the map depends on an alternative mechanism.”
This hypothesis is supported by indications that other migratory animals, such as birds and amphibians, may also have dual magnetic field receptors.
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