Some dolphins in Australia have developed a unique method to flush fish out from the seafloor — they use sea sponges balanced on their beaks, almost like a clown nose, to help with their hunt.

The sponge acts as a protective cover, shielding their sensitive beaks from sharp rocks as they dig through debris in sandy seabeds, stirring up barred sandperch for food.

However, this behavior — passed down across generations — is more complex than it appears, according to a recent study published in Royal Society Open Science.

Using a sponge impacts the dolphins’ echolocation ability — the biological sonar that helps them sense their surroundings by sending out sound waves and interpreting the returning echoes.

“It’s a bit like wearing a mask — it dulls the signals,” explained Ellen Rose Jacobs, a marine biologist from the University of Aarhus in Denmark and co-author of the study. “Things look a bit off, but the dolphins learn how to adapt.”

To study this, Jacobs used an underwater microphone to confirm that the sponge-using dolphins in Shark Bay, Australia, still relied on echolocation clicks to guide them. She then modeled how the sponge altered the sound waves.

For the dolphins that have mastered this technique, sponge hunting turns out to be a highly effective way to catch prey. The sponges they use vary in size, ranging from about a softball to a cantaloupe.

“It’s like trying to hunt while blindfolded — you need exceptional skill and training,” said Mauricio Cantor, a marine biologist at Oregon State University who wasn’t involved in the study.

That challenge may explain why the behavior is so rare — only about 5% of the dolphin population studied in Shark Bay use this strategy. That’s roughly 30 individual dolphins, according to Jacobs.

“It can take them years to perfect this unusual hunting method — and not all dolphins continue with it,” noted Boris Worm, a marine ecologist at Dalhousie University in Canada, who was also not part of the research.

Young dolphins typically spend three to four years with their mothers, during which they observe and learn vital survival skills.

This intricate sponge-hunting tradition is “taught exclusively from mother to calf,” said Janet Mann, a Georgetown University marine biologist and co-author of the study.

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