Scientists observing dolphins in Australia just made a remarkable discovery: these lively aquatic mammals use tools to help them capture fish.
The discovery, made near Queensland’s Great Sandy Marine Park, reveals dolphins use a foraging strategy called shelling, where the creatures chase small fish into an empty shell, then carry their captured prey to the surface and empty the shell’s contents into their mouths.
The new findings mark the first time this evidence of tool use by dolphins has been documented in video, and suggest that the activity may be taught to young dolphin calves by their mothers. The findings were described in a new paper that appeared in Marine Mammal Science.
Surprising Tool Use in the Animal Kingdom
Long thought to be a hallmark of culture that identified humans as unique among organisms on Earth, ongoing discoveries have revealed the ubiquity of tool use in nature.
From chimpanzees that engage in “engineering” using blades of grass, to crows engaged in the creation of “complex” tools, and even fish observed using rocks to help break open shells, tool use has proven to be a far more common strategy in the animal kingdom than once thought.
It isn’t surprising, therefore, that observations of dolphins near Queensland engaging in shelling had reportedly been observed by tour guides in Hervey Bay for more than a decade before the recent documentation of the behavior.
Similar evidence that pointed to the use of shelling in dolphin populations was previously documented in Shark Bay, Western Australia.
However, video of dolphins shelling obtained last October marked the first time this unique foraging strategy has ever been documented in footage. This provides a crucial new piece of evidence that not only shows the animals engaging in this behavior but also suggests that the technique is taught to young dolphin calves by their mothers, representing a form of social transmission.
Shelling Through Social Transmission
In the past, it was assumed that social transmission played a role in the emergence of shelling among dolphins, although more likely to be a practice among peers, rather than through maternal instruction.
“This aligns with other skilled foraging techniques such as sponge foraging,” said Alexis Levengood, a Lecturer in Animal Ecology at the University of the Sunshine Coast, in a recent commentary on the findings that appeared at The Conversation. “Because calves depend on their mothers for so long, they have plenty of time to learn from them.”
“So just like for us humans, mothers likely hold a very important role as a calf’s first and most important teacher.”
Remaining Questions
Levengood, who is also the lead author of a new paper describing the findings, says that there is still a lot to learn about this unique behavior she and her team have documented—a feeding strategy that had long been suspected in dolphins.
Presently, it remains unclear whether shelling is simply an opportunistic feeding strategy or if it emerged because it is a feeding method that reduces competition since it isn’t as common as other fishing techniques employed by dolphins.
“There’s still a lot we don’t know, and many questions we will hopefully ask and answer with time,” Levengood said.
“For now, all we can say is that within Australia some dolphins are shelling,” she adds, “and that this innovative tool use has spread from individual to individual by learning.”
The recent study, “Observations of Shelling Behavior and Potential Evidence of Vertical Social Learning by Bottlenose Dolphins in the Great Sandy Marine Park, Queensland Australia,” appeared in Marine Mammal Science.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.