I was recently interviewed and quoted for an MSNBC.com article by Kim Campbell Thornton - "Unlikely friends: Why we love odd animal pairs". You can read the article here. My quote is on the second page of the article addresses a bond between a hippopotamus and a tortoise.

It’s all the rage to email around special friendships between mixed species, usually featuring odd pairings such as a hippo and a tortoise or an orangutan and a dog. Often times it’s a series of pictures set to music and ends with deep messages like world peace can be obtainable.

My comment in the article deals with why a hippo might bond with a tortoise.
Photo © Bill Given.

Why do we draw such conclusions that animals from different species can in fact be friends? Are these relationships real and if so, what causes the development of such bonds? Be sure to read the article, I'm sure you'll enjoy it.