Some Australian dolphins use sponges to hunt fish, but it is more difficult than it seems

Washington – Some dolphins in Australia have a special technique to rinse fish from the seabed. They hunt with a sponge on their beak, like a clown nose.

Using the sponge to protect sharp rocks, the dolphins swim with their covered spouts, shoveling through the rubble at the bottom of the sandy canals and stirring sandpercased for a meal.

But this behavior – transmitted by generations – is more delicate than it seems, according to new research published Tuesday in the journal Royal Society Open Science.

Hunting with a sponge on their faces interferes with the feeling of finely adjusted echolocation of dolphins, emitting sounds and listening to echoes to navigate.

“He has a soil effect in the way a mask could,” said co-author Ellen Rose Jacobs, a marine biologist at the University of Aarhus in Denmark. “Everything seems a little weird, but you can always learn to compensate.”

Jacobs used an underwater microphone to confirm that the “sponge” dolphins in Shark Bay, Australia, still used echolocation clicks to guide them. It then modeled the extent of the distortion of the sound waves of the sponges.

For wild dolphins that have mastered food search with nose sponges, scientists say it is a very effective way to catch fish. Wild marine sponges vary from the size of a softball to a Cantaloup.

Sponge hunting is “like hunting when you have blindfolded – you have to be very good, very well trained to succeed,” said Mauricio Cantor, a marine biologist at Oregon State University, who was not involved in the study.

This difficulty can explain why it is rare – with only around 5% of the dolphin population studied by Shark Bay researchers by doing so. It’s about 30 dolphins in total, said Jacobs.

“They need many years to learn this special hunting skill – not everyone sticks,” said Marine Ecologist Boris Worm at Dalhousie University in Canada, who was not involved in the study.

Dolphins calves generally spend about three or four years with their mother, observing and learning crucial life skills.

The delicate art of sponge hunting is “that never transmitted from mother to offspring,” said Georgetown’s co-author and marine biologist, Janet Mann.

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