Green sea turtles, sharks, whales, penguins, and marine mammals have mysterious behavior, and they all do something unusual, swimming in circles unexpectedly.
According to an international team of researchers, there is no logical reason for doing so, and they tried to answer this question in their study published in the journal iScience on March 18th.
After recent technological advances have enabled researchers to track the movements of large animals, which live in the oceans with great accuracy, by recording data that can be represented in a three-dimensional manner, and reconstructing the movements of marine animals in spatial scales in meters and seconds, the researchers used this technology in an attempt to find An explanation of the phenomenon.
Search for a good reason
The team first discovered these mysterious spinning behaviors of green turtles, which were tracked by 3D data recorders.
Then they realized that various other species of marine animals exhibited roughly the same circular motions.
This finding is partly surprising, and researchers say this is surprising.
Because swimming in a straight line is the most effective way to get around, they suggest there must be a good reason for the animals to rotate.
They speculated that swimming in circles might help animals find food, be part of a mating ritual, or help animals discover magnetic fields they use to navigate.
Tomoko Narazaki of the University of Tokyo said in a statement to Scimex, "We found that a large group of marine megafauna exhibited a similar circular behavior, in which the animals were running at a relatively constant speed more than twice." .
And he suggests there must be a good reason for the animals to turn around.
Just like a machine
Narazaki's team first discovered mysterious spinning behaviors of green oriented turtles during their displacement experiment.
The team moved turtle nests from one place to another to study their navigation capabilities.
"Frankly, I doubted my eyes when I first saw the data, because the turtle is constantly spinning, just like the machine," Narazaki said.
"When I went back to my lab, I informed my colleagues about this interesting discovery, and suggested that they use the same 3D data recorders to study a wide range of species of huge marine animals," he added.
What happened next surprised the researchers even more. They realized that different types of marine animals exhibited roughly the same circular motions.
Narazaki's team reported that some spin events were recorded in animal foraging areas;
Which indicates that it may have some benefits in finding food.
For example, a total of 272 circular events were observed in 4 tiger sharks that were flagged off Hawaii.
However, fur seals are found to rotate mainly during the day even though they mainly forage at night.
Other events in the circulation also appeared unrelated to the search for food.
For example, they saw a male tiger shark circling around a female to courtship, and evidence suggests that the rotation may play some role in navigation in the case of sea turtles.
"What struck me the most was that guided turtles perform a circular behavior in locations that appear to be important from a navigational point of view, such as just before the final approach to their target," Narazaki says.
Green turtle tracks recorded by GPS (iScience)
Restrictions imposed
Rotation can help animals detect the magnetic field for locomotion;
But rotation can also serve more than one purpose.
Researchers say studying such subtle motions, including spinning, in more marine species may reveal important behaviors that were previously overlooked.
The researchers admit that their study lacks information about the surrounding environment such as landscapes, landmarks, and the presence of other individuals of the same species and / or other species.
Simultaneous analysis of high-resolution 3D motions and animal-borne video recordings may be useful for examining rotational motions in the context of social interactions and / or prey capture.
In future studies, researchers want to examine animal motions in relation to the animals' internal state and environmental conditions, in search of more clues and to draw clear conclusions about the causes of rotation.