Dolphins Name Themselves

"A high-pitched "wee-o-wee-o-wee-o-wee" whistle might not sound like much to you, but it's exactly how a dolphin might introduce itself.

Because sight is limited in the ocean, dolphins create individual "name" calls to communicate their whereabouts to friends and families.

But it's not as simple as just recognizing a voice, as with most animals. A new study reveals that the calls contain frequency changes that dolphins recognize."

http://www.livescience.com/animals/060508_dolphin_names.html