Bottlenose dolphins on opposite sides of Australia have independently developed a unique foraging behavior known as “shelling,” where they trap fish inside empty seashells. Researchers recently documented this tactic in Queensland’s Great Sandy Marine Park, confirming it mirrors a rare hunting method previously observed only in Western Australia’s Shark Bay.
Independent Innovation Across the Continent
Nearly 4,000 kilometers of coastline separate Shark Bay in Western Australia from Hervey Bay in Queensland, yet dolphins in both regions have arrived at the same complex hunting strategy. In a study published in Marine Mammal Science, researchers describe shelling
as a specialized foraging tactic that requires significant dexterity. The behavior involves locating a dead gastropod shell, coaxing a fish into the cavity, and carrying the shell to the surface to drain the water and capture the prey.
Because there is no plausible social or genetic link connecting the dolphin populations across such a vast distance, the study’s authors conclude the behavior was invented independently on both coasts. This suggests that similar ecological conditions—specifically the presence of large, empty shells and small fish seeking refuge—provided the necessary ingredients for dolphins to innovate the same solution to a common foraging challenge.
Field Observations in Great Sandy Marine Park
The research team, led by Alexis Levengood, has conducted surveys in the Great Sandy Marine Park since 2022. Their findings center on encounters recorded in 2025 involving Indo-Pacific bottlenose dolphins, known locally as buthu. During an observation on October 1, a mother dolphin named Maserati was captured by drone footage surfacing repeatedly with a baler shell.
The researchers observed Maserati using the shell, and drone video captured a fish escaping, followed by Maserati dropping the shell and chasing it.
The footage documented a fish escaping the shell, which Maserati then chased. Shortly after, her calf, Bentley, was observed performing the same maneuver, slapping the shell against the surface to extract prey. Earlier that year, on July 6, the team also followed a dolphin named Stevie Nicks, who manipulated a shell across three surfacings, though the team could not confirm if she successfully caught a fish.
The Mechanics and Learning Curve of Shelling
Shelling is considered a sophisticated form of tool use, but it is not a universal skill among dolphin populations. According to the research, the tactic is rare, fast and easy to overlook
because it requires precise coordination. The dolphin must not only find a suitable shell but also maintain the correct aperture orientation while ascending to ensure the water drains and the fish remains trapped.
The research indicates that this behavior is not universal; it requires a dolphin to locate a suitable dead shell, exploit a fish’s tendency to hide inside it, keep the aperture oriented during the ascent, and drain it without losing the meal.
While the team also identified photographic records from 2013 and 2019 that suggest shelling may have been present in Queensland for years, the 2025 encounters provided the first high-quality documentation captured on camera.
Broader Context of Aquatic Tool Use
Tool use in dolphins is not entirely unprecedented, though it remains a subject of intense study. Researchers at the South Carolina Aquarium have previously documented dolphins in the Charleston Harbor using the sides of commercial ships to assist in catching prey. In that instance, as with the Australian shelling, it was the first time that specific method had been recorded.
The Australian team intends to continue their research to understand why dolphins opt for such a labor-intensive method of hunting. Despite the success of the recent drone documentation, the researchers emphasize that they did not run a test that could reconstruct the exact first moment of invention
on either coast.
