Common turtle
And the magnetic field is its GPS: Study shows that these animals are able to memorize maps and perform specific movements when they identify a magnetic signature.
Some animals that travel long distances through the globe, such as birds, salmon, lobsters and sea turtles, are known to be oriented with the help of the magnetic field lines that cross the land from the north pole to the south pole.
Scientists already knew that these animals use magnetic information as a compass to determine their location, but new evidence reinforces the hypothesis that sea turtles, such as the common turtlethat nothing in every oceans on the planet are capable not only to orient themselves but also to create a complete magnetic map, establishing their favorite places to nest or to eat.
The study led by Kayla goforthfrom the University of North Carolina, provides the first “direct proof that an animal can learn and memorize the natural magnetic coordinates of a geographical area”. This means that turtles use the magnetic field as a GPS to create a map of their favorite locations.
But how does this happen? It is still a mystery, but scientists identified that turtles perform a series of movements, such as a dancewhen they identify a magnetic signature associated with food, for example.
The “Turtle Dance” in the Atlantic
The researchers found that the talent of turtles to create maps is independent of their internal measure, suggesting that these two forms of magnetic reception, one more linked to memory geographical and another to directionwork differently.
For the experience, scientists put young common turtles in a tank surrounded by a magnetic coil that replicated the magnetic field of the Atlantic Ocean.
The investigators changed for two months, daily, the magnetic field of the tank, simulating the conditions between the back of the United States and the Gulf of Mexico. Turtles were only fed when they received magnetic information from one of the areas.
When the animals anticipated that there would be food through the perception of the magnetic signal, they stirred their fins, opened their mouths and spinned in circles in the water. The investigators filmed this behavior, which was nicknamed “Turtle Dance”.
Turtles danced more enthusiastically in the tank when they knew there would be food, a “clear evidence” that they can learn the magnetic signatures of “specific geographical areas”, the study on Nature on February 12.
Even four months later, when tested again, the turtles still reproduced the movements when they identified the magnetic signature.
Magnetic reception mechanisms in migratory animals
Science does not yet know exactly how animals capture this magnetic information. A theory suggests that some may detect the influence of the magnetic field through a chemical reaction between light -sensitive molecules.
However, when researchers tried to interfere with this process using what is known as Radiofrequênci fieldsA, turtles continued to dance in the same place without changing their behavior.
In a separate experience that tested the internal compasses of the turtles, radio frequency produced lighter effects. In a tank that simulated the magnetic conditions of the Cape Verde archipelago in West Africa, radio frequency emissions seemed to disorient the turtle compasses, causing them to move in random directions.
The researchers concluded that “a reasonable hypothesis of work is that the meaning of the compass depends on the chemical magnetic reception, while the meaning 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 double recetors for magnetic fields.
