Winner – 11 to 14 years old: A mean mouthful by Sam Sloss, Italy/USA
On a diving holiday in north Sulawesi, Indonesia, Sam stopped to watch the behaviour of a group of clownfishes around their home, a magnificent anemone. It was only when he downloaded the photos that he saw tiny eyes peeping out of its mouth. It was a ‘tongue-eating louse’, a parasitic isopod that swims in through the gills as a male, changes sex, grows legs and attaches itself to the base of the tongue, sucking blood. When the tongue withers and drops off, the isopod takes its place.