Some Dolphins Use Tools to Hunt, Revealing Insights Into Cultural Transmission

A new study published in Royal Society Open Science reveals that the rare use of tools by wild bottlenose dolphins is shaped by significant sensory trade-offs that help explain why the behavior remains limited to a small subset of the population.

In Shark Bay, Western Australia, a small group of Indo-Pacific bottlenose dolphins use basket-shaped marine sponges as tools to hunt camouflaged fish hidden along the seafloor. While tool use has been observed in a variety of animal species, this behavior — known as “sponging” — is exceptional in its complexity, exclusivity and method of cultural transmission.

Led by Ellen Jacobs, a postdoctoral student at Aarhus University in Denmark who received her Ph.D. in biology from the College of Arts & Sciences last year, the international team of researchers used finite-element modeling to simulate how sponge tools affect dolphin echolocation — a key sensory system used for hunting and navigation. They found that the presence of the sponge significantly distorts the acoustic signals dolphins emit and receive, challenging their ability to detect prey using sonar.

“Sponging doesn’t just require finding, detaching and physically manipulating the tool — it demands that dolphins compensate for altered sensory input every time they use a sponge,” Jacobs said. “This makes the behavior cognitively demanding and difficult to master, which helps explain why it’s passed down almost exclusively from mother to calf.”

The study found that different sponge species impact sonar distortion in unique ways, and the most commonly used sponge, Echinodictyum mesenterinum, appears to interfere less with echolocation than other species of sponges, potentially influencing sponge choice. Despite frequent contact with non-tool using dolphins, no dolphin outside of the sponging matrilines has adopted the practice, underscoring how both biological and social constraints shape cultural learning in the wild.

“We have been studying sponge-tool use for over three decades and knew that it was a difficult technique to learn, potentially explaining why only offspring of spongers picked it up, but this work demonstrates the additional challenges of sponge tool-use and why primarily females engage in the behavior,” said Janet Mann, senior author of the study who is a professor of biology and psychology in the College of Arts & Sciences. “While sponge-tool use is clearly advantageous, spongers have to overcome the distortions introduced by the sponge — a bit like wearing the wrong prescription eyeglasses. Other dolphins occasionally acquire a sponge and try it out, but apparently just once. A calf would be exposed to thousands of hours of maternal sponging, and thus learns how to hunt effectively with this unusual technique.” 

The research adds a critical piece to the puzzle of animal culture, revealing how ecological challenges and sensory processing interact to constrain the spread of learned behaviors. It also highlights the sophisticated cognitive abilities of dolphins as they navigate the physical and sensory demands of life in the wild.

(Top image of a bottlenose dolphin named Whopper by Meredith MacQueeney, courtesy of the Shark Bay Dolphin Research Project)

Contact:
Ellen Jacobs
Georgetown University and Aarhus University
Email: erj22@georgetown.edu

Janet Mann
Department of Biology, Georgetown University
Email: mannj2@georgetown.edu

Paper citation:
Jacobs E, Wei C, Erbe C, Mann J. (2025) Cultural transmission of animal tool use driven by trade-offs: insights from sponge-using dolphins. Royal Society Open Science, 12: 241900. doi/10.1098/rsos.241900