Dolphins actually "name themselves" shortly after birth with their own unique whistle!

I think the "best kept secret" in all of science is that most animals and insects have some sense of self and that they too have their own unique "souls" so to speak.

Dolphins apparently create a signature whistle shortly after birth and share that whistle as if it were a name when they meet a new ally or dolphin:

From Discovery Magazine:
"... The signature whistles seem to act like badges of identity. One dolphin can learn information about another by listening to its whistle. But they’re not entirely like human names. For a start, they’re invented, rather than bestowed. They also convey more than just identity – they reveal the caller’s motivation or mood. "It’s a bit like in human language, where you can hear if a person sounds happy or sad, not in the choice of words they make, but in subtle acoustic features in their speech," explains Janik. ... 

[Link]