Marine biologists have been recording the "signature" whistles of captive dolphins for decades but have never been sure of their function. However a new study suggests that these personalised calls are in fact the the cetacean equivalent of shaking hands and trading business cards.

There are a lot of assholes in the ocean and just because two dolphin pods are of the same species doesn't automatically mean they'll play nice with each other. So when two pods meet in the open ocean, they'll each send ambassadors for an informal parlay. "It's not just 'I'm so-and-so,' but the other information also in that whistle is, 'I'm so-and-so, and I'm interested in making contact in a friendly way, I'm not attacking,'" said study researcher Vincent Janik, from the University of St. Andrews. Researchers had previously speculated that these signature whistles were simply the dolphins identifying themselves—which is amazing in its own right—but never anticipated this level of sophistication from the calls.

Janik's team deployed an array of submersible microphones around St. Andrews Bay to listen in on the Bays resident pod of Bottlenose dolphins as it interacted with other other groups. The team then parsed the recordings, applying statistical analysis to identify the signature whistles. They found that the two ambassadors would only produce these calls when the two groups met and subsequently merged.

The St. Andrew's team speculates that this behavior prevents the need for everybody in the pod to constantly introduce themselves, though the researchers were unable to confirm if a single dolphin was deemed the ambassador or if the duties rotated amongst the members.

"What I found really rewarding is to be out there and see how they communicate amongst themselves," Janik said. "These are wild groups that are just doing whatever they're doing. It's really the first time that we can pinpoint down two individual groups and how they interact in a vocal domain, which is really cool."

Very cool indeed. This could eventually lead to a full understanding of the dolphin language and perhaps even inter-species communication. Until then, we'll have to rely on Jim Carrey to translate on behalf of the cetacean community. [LiveScience via Neatorama]