(VIDEO) Australian Researchers Film Dolphins Using Seashells to Trap Fish, Revealing Rare Tool-Use Behavior

Scientists in Australia have captured the first published footage of dolphins on the country's east coast using large empty seashells to trap and catch fish, a discovery that suggests this rare tool-using behavior may have emerged independently in two dolphin populations separated by thousands of kilometers.

Researchers from the University of the Sunshine Coast recorded two separate sightings of the behavior, known as "shelling," among Indo-Pacific bottlenose dolphins in the Great Sandy Marine Park off Hervey Bay, Queensland, between July and October 2025. The findings, published in the peer-reviewed journal Marine Mammal Science, mark the first scientifically documented instances of the behavior anywhere on Australia's east coast. Until now, the only published evidence of shelling had come from a distinct dolphin population in Shark Bay, Western Australia, located more than 3,000 kilometers away, according to some measurements, or as much as 6,000 kilometers by other calculations of the distance between the two locations.

Shelling involves a dolphin chasing a fish into a large, empty gastropod shell — often a bailer shell, which can grow to roughly the size of a football — before lifting the shell to the water's surface and tipping it to drain the trapped fish into its mouth. Researchers describe the behavior as a genuine form of tool use, a trait considered rare among animals and one that has drawn significant scientific interest for what it may reveal about cognition and cultural transmission in non-human species.

Dr. Alexis Levengood, an animal behaviorist at the University of the Sunshine Coast and the study's lead author, described the moment her research team first spotted the behavior in the wild. "We were on a research boat off Hervey Bay when we spotted a dolphin raising something large out of the water. I started screaming because I know what shelling looks like," Levengood said.

Levengood further detailed the mechanics of the observed hunting technique. "It's a hunting behavior where dolphins chase fish into large empty shells, bring the shell to the surface and then shake it to drain the fish into their mouths," she said. "We were able to record footage and take photographs of dolphins shelling in the Great Sandy Marine Park, which is the first published record of it on the east coast of Australia."

Perhaps the most striking aspect of the discovery involved a second observation in which researchers captured what may be the first documented evidence of a young dolphin learning the shelling technique directly from its mother, a process known as maternal social transmission. According to the researchers, they observed an adult female dolphin surface with a shell, after which the trapped fish escaped and the dolphin dropped the shell to continue the chase. Minutes later, the dolphin's calf picked up the same discarded shell and held it in a manner similar to how its mother had handled it moments earlier.

Levengood explained the significance of that observation for scientific understanding of how dolphins acquire complex hunting behaviors. "Our footage provides the first potential evidence of maternal social transmission – a process by which offspring learn behaviour by observing the actions of its mother," she said. "It challenges the belief that dolphins learn this tool use from their peers." Previously, scientists had generally believed dolphins acquired shelling primarily through observing other dolphins within their broader social network, rather than through direct learning from a parent.

The research team also uncovered evidence that the behavior had likely been occurring in the Hervey Bay dolphin population for far longer than previously recognized, despite going scientifically undocumented. According to the researchers, conversations with local whale-watching tour operators revealed that shelling had actually been observed and photographed in the Great Sandy Marine Park as far back as 2013, with additional sightings recorded in 2019. Those earlier, informal observations had gone unreported in scientific literature due to limited dedicated research activity in the region, the team said.

The wide geographic separation between the two documented dolphin populations — one in Shark Bay on Australia's west coast and the other in Hervey Bay on the east coast — has led researchers to a striking interpretation: that both populations may have arrived at the same specialized hunting technique independently, rather than the behavior having spread through direct contact between the two groups, which are not known to interact given the vast distance and different oceanic regions separating them. Researchers cautioned, however, that while the documented behavior in both locations matches closely, their observations did not include a test capable of definitively reconstructing the exact original moment either population first developed the technique.

Levengood noted that shelling requires considerably more cognitive and physical sophistication than simply manipulating an object. A dolphin attempting the behavior must locate a suitable empty shell, understand that fish often seek shelter inside such shells, successfully position and maintain the shell's opening during its ascent to the surface, and then drain the shell's contents without allowing the trapped fish to escape, a sequence of coordinated steps that researchers say justifies classifying the shell as a genuine tool rather than an incidental object.

The discovery adds to a broader and growing body of research documenting tool use across the animal kingdom, a phenomenon once believed to be unique to humans. Some of the earliest documented evidence of tool use among non-human animals dates back to the 1960s, when primatologist Jane Goodall famously observed wild chimpanzees using sticks to extract termites from hollow logs, a finding that fundamentally challenged prevailing assumptions about the uniqueness of human tool use. Since then, researchers have documented numerous other examples across the animal kingdom, including primates using stones as hammers to crack open nuts and fruit, and separate populations of Shark Bay dolphins that have been observed covering their beaks with basket sponges torn from the seafloor, a technique that helps them forage for fish hidden in the sand while protecting their sensitive snouts from injury.

Reflecting on the broader implications of the new findings, Levengood emphasized how much remains unknown about the origins and spread of such behaviors among wild dolphin populations, while underscoring what the discovery reveals about dolphin intelligence more broadly. "There's still a lot we don't know and many questions we will hopefully ask and answer with time," she said. "But better understanding of shelling, and other tool use in non-human animals, will continue to teach us more about ourselves and how and why we evolved the way we did. These findings highlight how smart, clever and innovative dolphins are."

The research team plans to continue monitoring the Hervey Bay dolphin population through ongoing boat surveys, an effort researchers say could help clarify how widespread the shelling behavior actually is within the group and whether additional evidence of mother-to-calf learning can be documented in future sightings.