Dolphins have "names" they respond to Bottlenose dolphins can use learned vocal labels to address each other: http://www.pnas.org/content/early/2013/07/17/1304459110 Bottlenose dolphins use specific unique calls or whistles to refer to individuals, and each dolphin will respond to the special call for him/her. - my takeaway on the research. The animals create distinct sound patterns for each individual. This is an early preprint. Things may change later on.