A team of scientists has been studying penguins at London Zoo to try work out how the birds developed their distinctive waddle. The researchers from the Royal Veterinary College and the University of Texas have spent two weeks at the zoo encouraging the birds to walk on a track covered with sensors in order to provide a complete biomechanical picture of how they walk.

It is thought the birds did not always waddle and fossils suggest their ancestors moved very differently. Scientists say today's penguins probably developed their unusual walk as they became better adapted to swimming.

"I think that overall we are going to find that penguin waddling has a lot to do with the fact that they are so specialised for an aquatic existence. The thing that we are doing is trying to understand the minute detail of how waddling works in living penguins and then taking that back in time looking at the rich fossil record of penguins to understand how evolving for such a specialised underwater lifestyle has affected their ability to move on land," said James Proffitt from the University of Austin at Texas.

"Knowing how they actually evolved to walk like this is brilliant. What I have noticed is that penguins do move amazingly underwater but they do look a little bit clumsy on land. However, when they want to, they can actually move fast on land as well," said London Zoo's penguin keeper Zuzana Matyasova.

The team will now process the results of their study and report back.