Bearing curved black 'fangs', the tadpole of the Vampire Flying Frog Rhacophorus vampyrus from Vietnam is one of the strangest.
The moment I looked at the small, blackish tadpoles under the microscope, I knew they were special. In place of the usual tadpole mouthparts of small black jaw sheaths (resembling a very narrow “beaks”), surrounded by very tiny tooth rows, these little tadpoles had curved, black “fangs” sticking out of their mouths (bottom right in the image of the tadpole head above).
The tadpoles were so strange, that in 2010, my colleagues and I decided to name the newly discovered species to which they belonged after them. And so the Vampire Flying Frog (Rhacophorus vampyrus) was named.
Known only from cloud-forests on the Lang Bian Plateau in southern Vietnam, the adults are “flying frogs”, living in the trees and having webbed hands and feet. They’ve even taken their arboreal life so seriously that they don’t even come down to the ground to breed in ponds or streams- opting to lay their eggs in tiny, water-filled tree-holes.
Our recent examination of the external and internal anatomy of these tadpoles has revealed that it is this adaptation for arboreal life has resulted in their unique appearance. They’ve had to adapt to living crammed with their siblings in tiny amounts of water and little food, so their strange “fangs” and weird appearance are likely adaptations for egg-eating (oophagy), with their mothers returning to feed them unfertilised eggs (you can see the tiny cream-coloured eggs in the belly of the upside-down metamorph to the right).
It seems that, despite the scary name, Vampire Flying Frogs make great mothers!
The scientific publication describing the strange Vampire Flying Frog tadpole can be found in the Journal of Natural History: