Physics in the world of animals: sea turtles and their "compass"

Sea turtles can swim hundreds and even thousands of kilometers in search of food. But when it comes time to lay eggs, they can always return it to that beach where you were born. This fact is known to many hundreds of years, but only recently managed to explain. Sea turtles (lat. Cheloniidae) is a family of turtles of the superfamily Chelonioidea. This family includes a large sea and ocean turtles, which have a rounded heart-shaped or oval carapace covered with Horny shields, and neftehimiya limbs-flippers.

Most species of sea turtles live up to 80 years. They reach the sexual maturity in 30 years. At this time, females and male turtles return to the beaches where there was the light itself. Females lay 150-200 eggs in the sand, not too far from the water. Sea turtles are known for their ability to return to their beach and after many dozens of years after birth. Notable olive sea turtle. Her own kind EN masse back to several beaches, where they lay nearly in a single day hundreds of thousands or even millions of eggs. Turtle species of the Atlantic Ridley and is propagated on a single beach in the world located in Mexico.

Atlantic Ridley (Lepidochelys kempii) is a turtle species of the genus Ridley, individuals who are the smallest and simultaneously the fastest-growing of the family of sea turtles. Live in the Gulf of Mexico and the southwestern part of Florida. The species listed in the red data book of the IUCN and is under threat of extinction.

How these animals Orient themselves in space? As it turned out, do turtles have senses that allow them to sense the Earth's magnetic field and record the configuration in native places. In the future, the turtles are back in this kind of "snapshots" of the magnetic field. These animals are among the few species that are able to sense the Earth's magnetic field, using some of their needs. Except turtles are capable of migrating birds, some species of fish, several species of insects and bacteria.

The assumption that turtles may use geomagnetic field for navigation, expressed by different scientists at different times. Professor Kenneth Lohmann (Kenneth Lohmann) from the University of North Carolina at chapel hill decided to check if they are really. The problem was that experts did not know which organ in turtles could act as a compass.

"Sea turtles swim a thousand miles to return to the beach where they once hatched from the egg. For a long time we did not understand how they find their way back. We decided to check what role in this process is played by the Earth's magnetic field," says Roger brothers (Roger Brothers) from the University of North Carolina at chapel hill.

Fortunately, the specialists of the marine fauna is the results of long-term data for monitoring sea turtles. In particular, about 20 years, scientists have observed the movement of sea turtles of the species Caretta Caretta, lay eggs on the East coast of Florida. These data, the researchers decided to compare the information about the Earth's magnetic field at the same time.



The fact that the Earth's magnetic field from time to time changes its configuration. Using data on the dynamics of magnetic fields in certain regions of the planet, scientists have tried to predict the changing behavior of turtles. As it turned out, if magnetic marks are displaced, it changes the density of the masonry. If the labels are closer, the density of the masonry will increase, if the further — reduced.

"Probably, return to your beach for egg laying can be called the optimal solution. Conditions here are optimal," — said in a statement scientists.

Kenneth Lohmann was also able to prove that not only adults, but also small turtles know how to analyze the geomagnetic information. The fact that turtles after fall in the water, should do the long journey. They need to get over, which bathes the Sargasso sea. Here the juveniles spend the first years of his life. If a thousand will go wrong, and will float the wrong way, it can carry out in cold water, where to live sea turtle can not. They can also be caught up and current, which will carry them South, where living conditions are also not optimal. Therefore, for young turtles, it is vital to be able to navigate.



In order to show the ability of turtles to use geomagnetic information, they were placed in the pool, which was influenced by installing, reproducing magnetic field lines. This setting allowed to form a different configuration of the magnetic field. If the magnetic field lines showed avoidance to the North, the turtles swam South. If the configuration of the magnetic field was reversed — the young turtles swam North. According to experts, this is proof that for long journeys the turtles from birth are able to work with geomagnetic data.

Of course, the danger for turtles is not only in choosing the wrong path. On turtle eggs and turtles are hunted crabs, coyotes, gulls and many other species of animals, not to mention the man. Turtles of different age also hunt birds, sharks and humans. However, the main influence on the decrease in populations of marine turtles have still not animals, and people.

Source: geektimes.ru/post/281524/