Marine researchers in Japan and elsewhere have discovered another enigma of the aquatic world. In a new article published Thursday, they detail their finding that various species of large marine animals, from turtles to sharks and seals, swimming in circles for no clear reason. This circle could serve various purposes for the animals, such as helping their navigation or searching for food, the researchers say.
According to the researchers, recent advances in technology have allowed scientists to get a more complete picture of how animals in the ocean move through their environment with much better precision than before. Lead author Tomoko Narazaki of the University of Tokyo and colleagues decided to put this technology to good use by observing the movements of green sea turtles during their nesting season, when female turtles return to their birthplace to lay eggs.
They moved the turtles from their nesting site to another location, so that they could watch them navigate back to the original location. But once they did, they saw a peculiar pattern: The turtles often circled at a relatively constant speed at least twice, then returned to their normal swimming. as they ventured back home.
Curious, Narazaki told others in his field about the discovery. Finally, he partnered with some of these researchers to analyze motion data that had previously been collected on a variety of other marine animals on different branches of the evolutionary tree. And sure enough, they found that the same type of circular behavior appears repeatedly. These circling animals included fish (tiger sharks), birds (king penguins), and mammals (Antarctic fur seals and Cuvier’s beaked whales).
Your work is published on iScience.
“All the data used in our study were initially collected for different purposes (eg.g., to study the feeding behavior of sharks, etc.). The data for each species was analyzed by different co-authors for different aspects, ”Narazaki told Gizmodo in an email. “So, he took a time for us to realize that this circle is a common behavior in many species, until we collaborate. “
On the surface, circling It is impractical for the survival of these animals, since the most efficient way to travel to any part of the ocean is usually in a straight line. That probably means you have one or more important features that are worth the extra effort for. At this point, however, all the team has is some guesswork about what’s going on, which can vary between different species.
Sharks, for example, seem to circle more frequently around where they get food., indicating that it provides some advantage in hunting. Meanwhile, other research has displayed that some species of whales will use circles in groups as a way to create “bubble nets” to catch their small fish for prey. But feeding is probably not the sole purpose of tossing and turning.
In at least one male tiger shark, the team found evidence that circling was part of their courtship ritual in front of a female. Seals and penguins appear to circulate most frequently near the surface of the water or outside their typical fora.ging hours, which indicate that it is not part of your feeding technique. The team also cited previous research that found that northern elephant seals will spin around during their drift dives – lazy, passive dives that help them rest or process their last meal.
In turtles, going around in circles can help them reorient their navigation skills, which depend on in smell, sight and feeling magnetic fields. The turtles frequently circled just before the last leg of their journey, and for a time, as well. A turtle was observed to circle a whopping 76 times before continuing.
“Given that similar circular behavior was observed in a wide variety of marine megafauna taxa, it is possible that this is a behavioral convergence for similar purposes,” Narazaki said. “But for now, the purpose and function of this behavior remain unknown.”
Of course, we know that many animals on earth circulate for various reasons (just ask your nearest dog before pooping). But the darkness of the vast ocean means that there are probably all sorts of common behaviors among these animals that we just haven’t gotten to see. yet. Studying the how and why of Marine By circling closer, the researchers hope to illuminate this almost strange world a bit more.
“For the next step, we would like to examine the movements of the animals in relation to the internal state of the animals and the environmental conditions to examine why they go around in circles,” Narazaki said. “Some hypothesis-Trial experiments would be necessary to understand the function and mechanism underlying circular motions. “