Three varieties of "vegan Dracula" plant-eating lampreys found in unlikely places. Scientists are working to determine the full range of the ancient and elusive creatures that have lain hidden for 150 million-odd years.

With its suction-cup mouth and circular rows of sharp teeth, a close-up view of an Australian brook lamprey is rather frightening. But unlike many bloodthirsty lampreys around the world, this species prefers a plant-based diet, gobbling up organic matter on creek beds instead.