Bottlenose dolphins name themselves with distinct whistles, and use them to identify themselves within social groups.
Many species can make sounds specifically used for a certain purpose, such as mating, but it's not as common in the animal world to attach sounds to objects, The Guardian reported.
"If we look at complex ability in communication in human language, one of the key features that is important to us is that we can copy sounds, we can invent new sounds," Vincent Janik, a biologist at St Andrews University, who led the research, said. "We can then use those sounds and attach some kind of meaning to them and use them to refer to objects and to refer to external things in the world."
The signature whistles are used most often when the dolphins are traveling in their pack.
"Other contexts are particularly when groups meet at sea, they exchange information about who is present before the groups join, almost like a greeting," Janik said. "You also often find them between mums and calves if they get separated."
Janik's research team observed a group of about 150-180 dolphins living off the coast of Scotland "identifying and recording signature whistles and then playing these whistles back to the entire group."
The study found the dolphins would respond to their personal whistle, and call the same sound back, but would not respond to other dolphin's "names."
"The interesting thing about these is that they are not voice recognition," Janik said. "In humans you can have different people say the same word and I'd still be able to tell who's speaking. What we also do is have names, so they are very different call types. The dolphins do the same thing, they're developing a completely new call type, a melody or whistle, which is not dependent on their voice features."
"We show that they really react, they turn around. We even had some animals stop and come to the boat," Janik said, The Wall Street Journal reported
A spokesperson for the Whale and Dolphin Conservation charity says the research gives insight into dolphin's intelligence, according to The Guardian.
"We already know that they, like us, are self-aware [they recognize themselves in the mirror] and use tools to hunt for food. This evidence of their communication skills just adds to the growing body of emerging scientific evidence that demonstrates the existence of cetacean culture and that cetaceans are well developed cognitively," he said.
