Billy the dolphin teaches his flippered friends to walk on water

From an article by David Derbyshire in The Mail:

Like most dolphin trainers, Billie is patient and dedicated teacher.

Over the last few years, the 23-year-old has taught up to half a dozen wild dolphins how to tail-walk - the skill of 'walking' backwards through the water on their tails.

What makes the feat even more remarkable is that Billie herself is a bottlenose dolphin - the only known example of a mammal teaching human tricks to friends and family members in the wild.

Marine scientists have described the discovery as astonishing - and say it shows dolphins are even brighter than we realised.

Billie is thought to have learned the skill during three weeks in captivity in the early 1980s.

The female - who lives off the Adelaide coast in Australia - was captured by a local dolphinarium after she became trapped behind a marine lock and was unable to return to the sea.

After three weeks in a concrete tank she was released back into the wild with a '3' branded on her dorsal fin to make her easy to spot.

Billie returned to her usual haunts and - to the astonishment of dolphin experts - began to tail-walk herself.

Despite receiving no formal training, the scientists believe she learned the trick by watching her cell mates being fed for performing the tricks.

Now - more than 20 years after being released back into the wild - she is passing on the skill.