A wild female Indo-Pacific bottlenose dolphin was observed going through a series of complicated steps to prepare cuttlefish for eating in the Spencer Gulf, in South Australia.
Study co-author Tom Tregenza, from the University of Exeter, said the behaviour exhibited between 2003 and 2007 was unlikely to be a rarity.
"In addition to our observations, individual bottlenose dolphins feeding at these cuttlefish spawning grounds have been observed by divers in the area to perform the same behavioural sequence," they said in the study.
"The feeding behaviour reported here is specifically adapted to a single prey type and represents impressive behavioural flexibility for a non-primate animal."
The research team, writing in the science journal PLoS One, said they repeatedly observed a female dolphin herding cuttlefish out of algal weed and onto a clear, sandy patch of seafloor.
The dolphin, then pinned the cuttlefish with its snout while standing on its head, before killing it instantly with a rapid downward thrust and "loud click" audible to divers as the hard cuttlebone broke.
The dolphin then lifted the body up and beat it with her nose to drain the toxic black ink that cuttlefish squirt into the water to defend themselves when attacked.
Next the prey was taken back to the seafloor, where the dolphin scraped it along the sand to strip out the cuttlebone, making the cuttlefish soft for eating.
"It's a sign of how well their brains are developed. It's a pretty clever way to get pure calamari without all the horrible bits," Mark Norman, the curator of molluscs at Museum Victoria.
A separate 2005 study provided the first sign dolphins may be capable of group learning and using tools, with a mother seen teaching her daughters to break off sea sponges and wear them as protection while scouring the seafloor in Western Australia.
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