‘Sea turtles have evolved to use their flippers as hands’
Scientists discover that the marine creatures can carry and ‘karate chop’ prey using their limbs
SEA turtles have evolved to use their flippers as hands and even “karatechopping” prey, scientists have found.
Previously it was thought that the brains of the reptiles were too small to handle the dexterity required for ma- nipulating objects with their limbs.
Instead, it was thought they simply used their flippers to swim. But after scouring photos and videos of marine turtles, researchers at the Monterey Bay Aquarium in California have discovered the creatures use their flippers in surprising ways.
The images showed turtles carrying jellyfish prey and using a “karate-chopping” motion, rolling a scallop along the sea floor, grasping coral to eat, and pushing against a reef for leverage while ripping loose an anemone. In fact, the researchers identified at least eight different kinds of flipper manipulation, including “holding, digging, striking, tossing, leveraging, swiping, corralling, and pounding.” The animals were even seen licking their “fingers” after eating.
Dr Kyle Van Houtan, science director at the Monterey Bay Aquarium in California, who co-led the research, said: “Sea turtles don’t have a developed frontal cortex, independent articulating digits or any social learning.
“And yet here we have them ‘licking their fingers’ just like a child who does have all those tools. It shows an important aspect of evolution – that opportunities can shape adaptations.”
Three species were studied – the green turtle (Chelonia mydas), hawksbill (Eretmochelys imbricata), and loggerhead (Caretta caretta).
Similar behaviour has been observed in marine mammals with flipper-like limbs such as walruses, seals, and manatees.
But the resourcefulness of the turtles was unexpected given the small size of their reptile brains.
The findings, reported in the journal Peerj, provide insights into the evolution of four-limbed sea creatures and raise questions about “nature or nurture” – which traits are learned and which are hard-wired from birth.
Dr Van Houtan added: “We expect these things to happen with a highly intelligent, adaptive social animal. With sea turtles, it’s different.
“They never meet their parents; they’re never trained to forage by their mothers.
“It’s amazing that they’re figuring out how to do this without any apprenticing, and with flippers that aren’t well adapted for these tasks.”