The first time Sonja Wild saw a dolphin using an empty shell to pull an unconscious fish out of her mouth, she was so excited that she almost forgot to photograph it.
This rare and unique hunting technique is called “bombardment” or “shell.” A hungry dolphin will chase a hard-to-catch fish in an empty shell, then transport the shell to the surface where the dolphin uses its beak to push prey into its mouth.
“Seeing it for the first time was just a surprise moment because you don’t expect a shell to appear right next to the boat being transported by a dolphin. Like, you drop everything,” said Wild, a behavioral ecologist at the University of Konstanz and the Max Planck Institute for Animal Behavior in Germany.
“I was definitely amazed,” she said. How does it happen Guest host Duncan McCue.
Wild is the primary author of a new study in the journal Current Biology That documents how the shell has spread through dolphin populations as smart creatures teach each other how to do it.
Scientists have observed cases of shells dating back at least 10 years, although it has always been rare.
Wild says there was a huge increase in sightings in Shark Bay, off the coast of Western Australia, after a 2011 ocean heat wave killed a large number of sea snails, leaving their mature shells for harvesting.
Wild and his colleagues have been watching Shark Bay dolphins for years, mapping their social and genetic relationships. Between 2007 and 2018, they identified 1,000 individual dolphins and saw 19 of them participate in shells 42 times.
While the shell appears to be quite rare, Wild says that all the dolphins that make it know each other.
Analyzing data from their population, the researchers found that the conch extends horizontally within generations of dolphins – that is, from pair to pair, rather than vertically, from mother to calf.
“That is quite special because dolphins typically rely heavily on their mothers for feeding behavior,” said Wild.
“And now we are demonstrating for the first time that they are, in fact, capable of learning feeding behaviors outside the mother-calf bond.”
Janet Mann, a dolphin researcher at Georgetown University who was not involved in the study, he told the New York Times It is impossible to say definitively that peer-to-peer imitation is the only way that dolphins learn about the shell, noting that “we have barely scratched the surface of the water” when it comes to understanding behavior.
Wild agrees.
“It is quite possible that some dolphins have learned this for themselves, simply by interacting with their shells and then, by accident, lifting them above the surface,” he said.
She says some dolphins may also be passing the skill on to their young. But her team’s models “clearly show that most have learned from their peers.”
Why do they do it?
Wild says she is not sure why dolphins use shells to catch and eat fish.
She says they are very playful creatures, and that it could be as simple as “a little fun to get your food in a different way than usual.”
But whatever their motivation, it shows that they can adapt to a changing environment and acquire new skills, a skill that could help them survive as climate change disrupts ocean populations and makes food scarcer, he said.
“Learning from your mother is very useful in a type of stable environment that does not change, because the behavior of the parents is tested and stable and adapted to the environment. But as soon as the environment changes, the behavior can become obsolete or inefficient or even maladaptive, “Wild said.
“And in that case, it’s beneficial if you start looking around to see what other dolphins are doing.”
‘Humans are not the only ones with culture’
Wild said learning new tricks from friends is rare in the animal kingdom. It is a form of learning that is generally only observed in primates, including apes, chimpanzees, and, of course, humans.
“It certainly helps us understand their intelligence by knowing that they are capable of innovating such remarkable behavior, but it also helps us understand that dolphin societies may not be so different from us humans,” said Wild.
“They have very complex social relationships. They use tools. They can learn to use each other’s tools. Therefore, it helps us understand that humans are not the only ones with culture.”
Written by Sheena Goodyear Interview produced by Katie Geleff and Jeanne Armstrong.
