Now, scientists have discovered how these dolphins learn to catch their prey in this extraordinary way, using their beaks to bring the shells to the surface and then shake the fish in their mouths, similar to how humans reach those latter. chips in the bottom of a package
“Our study shows that ‘bombardment’ feeding behavior – where dolphins catch fish inside empty seashells – it extends through social learning among close associates, “said Sonja Wild, who conducted this research for her PhD at the University of Leeds.
“This is surprising, as dolphins and other toothed whales tend to follow a” do what the mother does “strategy to learn feeding behavior,” he said in a press release. Mothers and young of dolphins often form very close bonds, staying close to each other for at least two years learning social behaviors and feeding techniques.
The findings provided further evidence of similarities between dolphins and great apes (chimpanzees, gorillas and humans) that have also shown a variety of socially learned foraging behaviors, said the study, published Thursday in Current Biology.
“Despite their divergent evolutionary histories and the fact that they occupy such different environments: both dolphins and great apes are long-lived, big-brained mammals with high capacities for innovation and cultural transmission of behaviors,” he said. Michael Krützen, director of the department of anthropology at the University of Zurich and lead author of the study.
Using boats, the international team of researchers conducted surveys in the western gulf of Shark Bay, Australia, between 2007 and 2018 to assess how the bombing behavior spread in the population.
In 5,278 encounters with dolphins during that time, scientists identified 1,035 Indo-Pacific bottlenose dolphins (Tursiops aduncus). They saw 19 dolphins in the act of bombing 42 times.
Although the bombardment seems quite rare, both the number of bombardment events and the number of individual “launchers” are likely underestimated, according to the study, as the shaking of the shell only lasts a few seconds and is therefore difficult to observe.
“Some dolphins use shells quite frequently during foraging, while others have only been seen with a shell once,” said Wild. “So while there may be other explanations, some dolphins may have mastered the skill more than others.”
The social network
To discover how this form of feeding had spread from one dolphin to the next, the researchers analyzed the influence of environmental factors, the genetic predisposition and the dolphin social network.
The model they developed showed that dolphins learn the bombardment from associates within their social group, and concluded that the use of shells spreads mainly within generations, rather than between generations, providing the first evidence that Dolphins are also able to learn from their partners, not just from their partners. mothers
The shelling is only the second reported case of tool use on dolphins. According to the researchers, dolphins in the same area are also known to use sea sponges as feeding tools to help them catch prey.
Wild said a 2011 ocean heat wave wiped out Shark Bay’s critical seagrass habitat and killed fish and invertebrates, including gastropods (sea snails) that live in the giant shells. She said the resulting abundance of dead giant gastropod shells may have made it easier for dolphins to learn this behavior.
“Our results show that dolphins are definitely capable and, in the case of shelling, they are also motivated to learn new feeding tactics outside of the mother-calf bond,” said Wild.
“Learning from others allows a rapid spread of novel behaviors among populations, and it has been suggested that species with the ability to learn from others in this way may survive better,” he said.