Within the first few months of life, every bottlenose dolphin invents a unique whistle that becomes its name for the rest of its life — and other dolphins learn that whistle, remember it, and use it to call out to that specific individual, making bottlenose dolphins the first non-human species ever discovered to use personal names
https://spacedaily.com/d-within-the-first-few-months-of-life-every-bottlenose-dolphin-invents-a-
