By Liz Langley 7-9 minutes
PUBLISHED June 25, 2020
Bottlenose dolphins hunt in French Polynesia’s Rangiroa Channel. The marine mammals use two types of tools to find food, a rare behavior in nature.Photograph by Greg Lecoeur, Nat Geo Image Collection
In Shark Bay, Australia, bottlenose dolphinsthat aren’t related have been observed teaching each other a new way to use a tool, a behavior that until now scientists have found only in humans and other great apes.
It’s also the first known example of dolphins transmitting such knowledge within the same generation, rather than between generations. That’s significant, the authors say, because such social learning between peers is rare in nature.
In a practice called shelling, dolphins will chase fish into abandoned giant snail shells on the seafloor, then bring the shells to the surface shake them with their noses, draining the water and catching the fish that fall out.
Dolphin mothers generally teach their young how to hunt: Shark Bay dolphin moms, for instance, teach their offspring sponging, another form of tool use in which dolphins put sponges on their beaks to protect them while foraging among rocks. (Explore our interactive of the tools animals use.).
A Shark Bay dolphin practices shelling, one of only two known examples of tool use in the cetaceans.Photograph by Sonja Wild, Dolphin Innovation Project
“The fact that shelling is socially transmitted among dolphin peers rather than between mother and offspring sets an important milestone, and highlights similarities with certain primates, who also rely on both vertical and horizontal learning of foraging behavior,” senior study author Michael Krützen, an anthropologist at the University of Zurich, said in a press statement.
Though dolphins and great apes have very different evolutionary histories and habitats, they’re both long-lived, large-brained mammals with tremendous capacity for innovation and culture, Krützen says.
Maggie Stanton, a psychologist at Franklin & Marshall College in Pennsylvania, who has studied Shark Bay dolphins and chimpanzees at Tanzania’s Gombe Stream National Park, agrees. One chimp family in Gombe, she notes, may have learned how to use tools to extract ants from a female chimp that joined the community.
Cracking a mystery
In 2007, Krützen launched a study of Shark Bay’s dolphins, identifying more than a thousand individual dolphins over 11 years. During this time, scientists observed shelling 42 times among 19 dolphins. Half of these events occurred after a marine heatwave in 2011, which may have caused a die-off among giant sea snails, leading to more discarded shells on the seafloor. (Read about a new species of dolphin discovered in Australia.)