Bottlenose dolphins have whistles that they use to exclusively greet other members of their species, say marine biologists.
Bottlenose dolphin (Tursiops truncatus) is one of only very few species which can invent or copy noises.
Using hydrophones, Vincent Janik and Nicola Quick of the University of St. Andrews, made recordings of dolphins swimming in St. Andrews Bay, off the northeastern coast of Scotland, in the summers of 2003 and 2004.
They heard that when groups of dolphins met up, they swapped whistles that outwardly sounded the same.
But forensic analysis revealed the whistles were in fact individual signatures, for they were never matched or copied by other dolphins, the Telegraph reported.
“Signature whistle exchanges are a significant part of a greeting sequence that allows dolphins to identify conspecifics [members of the same species] when encountering them in the wild,” according to the study.
The whistles are clearly important, as they were heard in 90 percent of the joinups, the study added.
One particular signal came from what appeared to be the leader of a group, seemingly giving the OK to fellow dolphins in the team to join up with the other group.
Other whistles could be about agreeing roles to hunt for food or identifying individuals for socialising.
Bottlenose dolphins operate in a “fission-fusion” society, meaning they live in groups that are fluid in numbers.
The study appeared in the British journal Proceedings of the Royal Society B.