Silhouetted against a blue background, it looks like these tadpoles are flying through the air – but the picture was in fact captured under water.

The baffling image, something of an optical illusion, has claimed first prize in the first ever Royal Society Publishing photography competition.

Captured by biologist Bert Willaert, the unusually-angled shot was taken while the snapper was snorkeling in a canal in his native Belgium.

It was chosen as the winner by a judging panel of scientists, including multiple winner in the Wildlife Photographer of the Year contest, Professor Alex Badyaev.

Bert, a biologist of amphibian evolution, said: “Clear water is hard to come across in the part of Belgium where I live, as a consequence of eutrophication. Algae grows from the nutrients flushed down the drains in detergents and sewage, clouding the waters and suffocating other oxygen-dependent life. When I noticed these common toad tadpoles in the crystal clear canal I wanted to capture the chance encounter from their perspective. To conserve the natural world, drawing attention to the beauty of ordinary moments in our neighbourhoods, including our own backyards, is important. I believe people will only conserve things when they know it exists – and how often will people have had snorkeled in their own garden pond?”

The winning photo was chosen from more than 1,000 entries.

bbabo.Net