Dolphins give themselves unique "names" made of whistles

Bottlenose dolphins develop their own unique sound pattern early in life, called a signature whistle — something like a personal "name" they use to identify themselves within the group.

Other dolphins in the pod learn to recognize these whistles and can deliberately repeat someone else's signature sound to call that specific individual over — much like a person calling someone by name.

In recordings, researchers have observed mother dolphins repeating their calf's whistle after becoming separated from it, and dolphins remembering and responding to the whistles of familiar individuals even after twenty years apart.

This is one of the very few confirmed cases in the animal kingdom of an individual having something functionally very close to its own name, used deliberately by other members of the group.