Dolphins call out the "name" of a loved one they want to be reunited with, a study has found.
The dolphins are known to use their own signature whistle to introduce themselves to others.
Now experts have shown that a calf separated from its mother mimics her short, sharp whistle in what is thought to be a way of trying to trigger a reunion and a male will use the same method to try to find its best friend of the same sex, the Daily Mail reported.
Researchers at St Andrews University analysed recordings of bottlenose dolphins from Florida that were periodically caught for health checks.
During these checks the dolphins could normally hear, but not see, each other.
Information on captive dolphins at Walt Disney World, also in Florida, was factored in and the data showed that when two close male friends were separated, one often mimicked other's whistle, the same was true of mothers and calves.
The whistle wasn't an exact copy, suggesting that they weren't using mimicry as a way of deceiving other dolphins about their identity nor did it seem to be an act of aggression.
Researcher Stephanie King said that the signature whistle copying was only found in pairs of animals composed of mothers and their calves or adult males who form long-term alliances with one another.
The study has been published in journal Proceedings of the Royal Society B. (ANI)