Researchers at the Monterey Bay Aquarium (United States) have discovered that sea turtles use their fins to handle prey, even though the limbs are evolutionarily designed for locomotion.
The in-depth examination of the phenomenon by the authors Jessica Fujii and Kyle Van Houtan and other scientists reveals that this behaviour is widespread, although it was thought to be less likely in marine tetrapods. Specifically, they discovered that this type of finning might have been happening 70 million years earlier than previously thought.
“Sea turtles do not have a developed frontal cortex, independently articulated digits, or any social learning,” says Van Houtan, Director of Science in the aquarium. “And yet, here we have them ‘licking their fingers’, like a child who has all those tools, it shows an important aspect of evolution, that opportunities can shape adaptations,” he adds.
Lead author Jessica Fujii is part of the aquarium’s marine otter research team, where she specializes in Ecomorphology: the intersection of evolution, behaviour and body shape. Fujii’s experience in sea otter feeding and the use of tools has influenced his recent examination of sea turtles and how they have evolved to use their limbs in novel ways.
The analysis of Fujii and Van Houtan using photos and videos finds widespread examples of behaviours such as a green turtle holding a jelly, a loggerhead rolling a scallop shell on the seabed and a hawksbill pressing against a reef to leverage an anemone.
Similar behaviours have been documented in marine mammals, from walruses to seals and manatees, but not in sea turtles. The document shows that sea turtles are similar to the other groups in which the fins are used for a variety of foraging tasks (clamping, reinforcement or corralling).
“The limbs of sea turtles have evolved mainly for locomotion, not to manipulate prey,” says Fujii. “But what they are doing anyway suggests that, even if it is not the most efficient or effective way, it is better than not using them at all,” he adds.
The finding was a surprise to the authors, given the ancient lineage of sea turtles and the fact that reptiles are considered to have simple brains and simple fins. The results also offer insights into the evolution of oceanic creatures from four branches that raise questions about what traits are learned and which are programmed.
“We hope these things happen with a highly intelligent and adaptive social animal,” says Van Houtan. For his part, Kyle points out that with sea turtles it is different because they never meet their parents. “They were never trained to feed by their mother, it is surprising that they are discovering how to do it without any kind of learning, and with fins that are not well adapted for these tasks,” says the researcher.
Source: La Vanguardia
Daily Mail UK