By Matt Walker
Editor, Earth News
Wave the dolphin, tail-walking
Wild dolphins in Australia are naturally learning to "walk" on water.
Six dolphins have now been seen mastering the technique - furiously paddling their tail fluke, forcing their body out and across the water.
The dolphins seem to walk on water for fun, as it has no other obvious benefit, say scientists working for the Whale and Dolphin Conservation Society.
That makes the behaviour a rare example of animals "culturally transmitting" a playful rather than foraging behaviour.
Only a few species are known to create their own culture - defined as the sharing or transmitting of specific novel behaviours or traditions between a community of animals.
The discovery was made by Whale and Dolphin Conservation Society (WDCS) scientist Dr Mike Bossley, who has spent 24 years studying dolphins living in the Port River in Adelaide, Australia.
In past years, Dr Bossley has witnessed two wild adult female dolphins, named Billie and Wave for research purposes, attempting to walk on water.
Now four other dolphins, including young infants, have been recorded trying to learn the trick from the two adults, and have been seen practising, less successfully, in the river.
The behaviour, when a dolphin beats its tail fluke repeatedly, so it lifts its body vertically out of the water and then along the surface, is more commonly seen among captive dolphins trained to perform tricks.
A composite image showing Bianca the dolphin attempting to tail-walk on 10 Oct, 2010
In the wild it is extremely rare.
According to the WDCS, apart from Billie and Wave, only one other adult dolphin had previously been seen tail-walking in the Port River during thousands of hours of scientific observations, and then only once.
Billie is thought to have learned the trick during a brief period when she was held captive in a dolphinarium, before being released back into the wild.
She passed the behaviour onto Wave, and now Billie and Wave appear to be passing on their knowledge of how to tail-walk to their wider community.
WDCS dolphin photographers Marianna Boorman and Barbara Saberton have recently documented Wave's calf, named Tallula, also attempting to tail-walk.
Other dolphin called Bianca, and her calf Hope, and another calf called Bubbles are also attempting the trick.
These dolphins are now being seen trying to tail-walk many times each day.
A number of animals are known to culturally transmit novel behaviours to others of their species.
Bianca the dolphin photographed tail-walking on 18 October, 2010
Chimps learn to fish for termites with sticks, and orcas learn various techniques to hunt seals, for instance.
But few examples have been documented of animals culturally passing on behaviours that are unrelated to obtaining food.
Tail-walking appears to have no function other than play, says Dr Bossley.
"As far as we are aware, tail-walking has no practical function and is performed just for fun, akin to human dancing or gymnastics," he says.
"Culture in the wider sense of the term, defined as 'learned behaviour characteristic of a community' is now frequently on show in the Port River."