The sea turtle was a bad navigators

When trying to reach remote oceanic Islands for the green turtle (Chelonia mydas) are often mistaken with the choice of the direction and correct it only when you miss hundreds of kilometers away, reported in Current Biology. Data on the movement of reptiles in the open ocean, as earlier laboratory experiments show that the mental map of the area from green turtles are quite approximate, but they are able to adjust the direction of the open ocean without any external reference points.

Green turtles most of my life spend some shores, where they feed aquatic vegetation, but every few years they migrate for breeding to other, remote on the thousands of miles of land. Eggs, they return to usual feeding places. They probably don’t even eat on the way: at least the turtles definitely do not stay on the appropriate for food places along the way.

As reptiles find their way to their interested points is not clear. Most of the data about the navigation of green turtles obtained from the analysis of the cases, when the animals were close to the usual food places near the shores of continents and large Islands like Madagascar. In this case, to reach the desired point is quite simple: at the coast there are visual landmarks. But in the case of movement to the small Islands in the open ocean to take advantage of them not work, and the necessary additional tools to help not to miss the target, or at least after failing to correct the trajectory to get to the right place in the foreseeable future.

Zoologists from the University of Swansea (UK), headed by Nicole Esteban (Nicole Esteban) analyzed information from the GPS sensors mounted on a 33 female green turtles that in 2013, 2015, 2017 and 2018 have made migration from the island of Diego Garcia, where they sailed for breeding back on feeding places in the Western part of the Indian ocean. Every six hours each device is transmitted on the whereabouts of individual turtles, and researchers have built according to the data of the trajectory of individuals, based on the assumption that hungry animals will not be long to stop and turn towards the food.

What guided the green turtle in the choice of destinations is not known. There are two possible mechanisms: a magnetic compass and the so-called real navigation. The first implies that the animal moves to the desired point in azimuth, the second is that the body has a mental map of the area, which he should. These options can be combined. The researchers simulated 16 paths of green turtles, given the hypothesis that these animals only use the real NAV, and compared them with the real.

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