Who'd have thought it? Nobody apparently. A newly discovered species of fanged frog indigenous to Indonesia's Sulawesi Island has scientists scratching their heads. Limnonectes larvaepartus is the first known anura to give birth to tadpoles.

Most frogs lay eggs which are then externally fertilized, and left to hatch as and when their moment arrives. To date, as few as 12 of the world's 6,000 recorded species are have been observed using internal fertilization practices, and all of them either give birth to fertilized eggs or more highly developed froglets.

The international team of researchers responsible for the Sulawesi find, which was #link:http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115884:published in Plos One#, are excited by the find. But the new phenomenon remains a scientific mystery, not least because male frogs don't have the sexual organs needed to transfer their sperm for internal fertilization.