In a video released alongside a fascinating new study, scientists are on a boat in the turquoise waters of Shark Bay, Australia watching four adult male dolphins, their dorsal fins jutting out of the calm bay. The dolphins are doing the previously unheard of: calling each other by name through a series of whirling clicks, buzzes, and high-frequency whizzes.

Off-camera, study co-author Stephanie King, Ph.D. murmurs, “This is the coolest thing ever.”

What is so unmistakably cool to King is that she can hear each adult dolphin male’s individual voice label — in short, their name. In a study published this week in Current Biology King, a research fellow at the University of Western Australia, and her team note that it’s been known that bottlenose dolphins are adept at producing sounds and develop individually specific signature whistles within the first few months of their life. The working theory has been that once mature male dolphins team up with small alliance crew, they ditch their individual “names” and share the same signature whistle.

According to this new study, based off a decade’s worth of research, that’s not the case: Besides humans, dolphins appear to be the only animal that retains its individual “name” throughout its life and uses that name as a tool in forming close, long-lasting relationships.

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Male dolphins, despite their strong social bonds, retain their individual whistles to identify their partners and competitors. 

“This is a very unusual finding,” co-author and University of Zurich professor Michael Krützen, Ph.D. announced in a statement released Thursday, noting that it’s common for pairs of animals to share a similar call to build and maintain their bond. “With male bottlenose dolphins, precisely the opposite happens: Each male keeps his own, individual call, and distinguishes himself from his allies, even when they develop an incredibly strong bond.”

In addition to calling each other by name, the researchers found that the male dolphins also express their social bonds through physical signals like synchronized behavior, caressing, and slapping — something like the equivalent of football player swatting the bum of his teammate.

These bromances have previously been documented in Shark Bay, and the alliances are crucial for one main thing: helping each other get access to females. Male dolphins typically have their main crew, and then another group of second-order alliances. In this study, the scientists were able to recognize which dolphin was in each alliance group by referencing photo identification records kept on Shark Bay dolphins over the past 10 years.

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Within their population, male dolphins enter into complex, multi-level alliances.

For this study, the scientists observed these various alliance groups by using underwater microphones to make recordings of the dolphin’s whistles. For each of the 17 adult male bottlenose dolphin they followed, they were able to pinpoint a signature whistle to each of the dolphins. These dolphins used these whistles to identify each other in both their first order alliances and in their different second-order alliances.

It’s this complex communication system, the scientists write, that likely underlies the “social cognition required for the formation of social alliances, facilitating both partner choice, and the execution of coordinated behaviors.” It’s also a remind that they are very, very intelligent — complex animals kept back from advancement because of their lack of thumbs.