"What to do with all that intellectual firepower? Primp in the mirror, of course. Dolphins have passed the famed mirror self-recognition test, which bespeaks possession of an inner life and a concomitant concern with its packaging. When presented with a mirror, dolphins take the opportunity to check their teeth and body parts they can't normally see, like their anal slit.

Or why not become a slave to fashion? One day, a killer whale in Puget Sound started pushing a dead salmon around in the water. The other whales in her community thought that was "really cool," Dr. Whitehead said, "and within a few weeks, everybody had a dead salmon they were pushing around." By summer's end, the fad was over, and the behavior was never seen again.

Yes, brainy cetaceans love to play copycat. When a wild bottlenose dolphin was injured in Australia and taken into an aquarium for rehabilitation, the mammal learned from its captive tank mates the trick of using its tail to walk on the surface of the water. On being released back into the ocean, the dolphin continued to tail-walk, said Dr. Whitehead, "and soon the other wild dolphins started doing it, too." Cetaceans are master mimics. "One prominent chimp scientist admitted that dolphins ape humans better than apes do," said Dr. Whitehead.
..."

New York Times, 6-28-10