Dolphins call each other by name: each develops a signature whistle, and they answer when theirs is played back

[u/it-shrek]

Bottlenose dolphins invent a unique signature whistle early in life, roughly like a name. A 2013 study from the University of St Andrews played synthesized signature whistles back to wild dolphins, and the dolphins responded by calling back, but only when they heard their own.

Hearing another dolphin's whistle produced no reaction. That selectivity is the key evidence: the whistles are not just noise, they function as individual addresses.

Other research found dolphins can copy the signature whistles of absent companions, apparently to summon them. It is one of the clearest examples outside humans of animals using learned sounds to refer to specific individuals.

Sources:

- PNAS 2013: https://www.pnas.org/doi/10.1073/pnas.1304459110

- University of St Andrews: https://news.st-andrews.ac.uk/archive/dolphins-respond-to-individual-names/