Growing up, I was lucky enough to occasionally join a group of scientists aboard a research vessel off the northern tip of the Bahamas. We would spend hours a day and up to two weeks at a time on the open ocean swimming with them and making visual and audio recordings of their behavior. The species they study are Atlantic Spotted Dolphins (Stenella frontalis). One of the things that has always struck me about them is how social they are – they have social circles and "cliques", similar to humans. We would observe these social networks and monitor how they change over the years. This research project is unique because they've been following this same group of just a few hundred dolphins in the wild for over 25 years. Having watched video and high frequency audio recordings of them interacting with one another in the wild, it comes as no surprise that they have "names" for one another.

Relatedly, Denise Herzing, the founder of that organization (the Wild Dolphin Project) will be speaking at TED this year (see Session 8, "Coded Meaning"): http://conferences.ted.com/TED2013/program/guide.php

Here's their site: http://www.wilddolphinproject.org/about-us/mission-vision/