Marine researchers in Australia’s Great Barrier Reef were astounded when they saw a bottlenose dolphin chasing a bigeye trevally until it vomited, before eating what the fish had just spewed up.
Romney Edwards-Francis, a PhD candidate at University of the Sunshine Coast in Queensland, first saw the unusual behaviour while snorkelling on a visit to Lady Elliot Island Eco Resort for the Leaf to Reef Project.
Edwards-Francis had heard from master reef guide Pieter Demmers and marine biologist Jacinta Shackleton that a dolphin called Bubbles, who often visits the island, was known for a strange behaviour. “He basically chases this one fish. The fish throws up. He eats the vomit,” explains Shackleton.
She’s seen this happen several times. Bubbles even seems proud of his smart hunting strategy. After gobbling down the barf, “he turns his head straight towards me, does this really long click, and it's almost as if he's saying like, ‘Look what I did! I got the food. I'm so smart.’,” she says.
Edwards-Francis and colleagues also saw this happen. “It wasn’t until we finished our snorkel that we realised we’d caught it on camera,” she says.
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The behaviour is a type of kleptoparasitism, which means stealing food from another animal. “It’s a form of parasitism because it doesn't benefit the trevally… other than they get to live,” says Shackleton.
Realising that this was something that had never been documented in dolphins before, the scientists published their findings in the journal Ecology and Evolution.
The paper includes 20 records of Bubbles foraging between June 2021 and October 2025, 11 of which resulted in the dolphin eating the fish’s regurgitated prey.
Frigate birds exhibit a similar behaviour. They lock onto a white capped noddy that has been feeding and chase it through the air. “It's like a V8 supercar race,” says Shackleton. “They'll stress this poor noddy out so much that the noddy will throw up all of its fish, and then the frigate bird just comes in and plucks them off the surface of the water.”
Their theory is that forcing the fish to throw up their recent meal is easier than hunting live prey.
It’s hard to know how much energy the crafty dolphin might be saving through this cunning strategy but the researchers think he probably still hunts most of his food.
“I’d speculate that the trevally vomit provides an easy snack on days when Bubbles hasn’t been as successful with hunting, especially as the bigeye trevally school is very reliably found in the same location nearly every day,” says Edwards-Francis, the study’s lead author.
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The scientists think this is the first time this odd foraging strategy has been documented in dolphins. But the fact that only Bubbles has been recorded doing it doesn’t mean others aren’t too. “It’s very possible that other individuals also use this tactic,” adds Edwards-Francis. “These behaviours are really difficult to observe under the water and you have to be in the right place at the right time to capture it.”
Shackleton loves telling her guests about this bizarre foraging method because fascinating facts like this can help get people interested in science. “I watched people's faces be like, ‘Eww, that's disgusting’,” she says, “but also, I could see they were so interested by the fact this dolphin was really smart.”
The team would love to hear from other researchers around the world who may have seen a similar behaviour. “They’re possibly much more common than we realise,” says Edwards-Francis. “Documenting them provides a snapshot of the complex and varied tactics wild animals use to survive.”
Find out more about the study, published in Ecology and Evolution.
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Top image: Bubbles the vomit-eating dolphin. Credit: Pieter Demmers
