New Species of Fanged Frog Gives Birth to Live Tadpoles

Researchers have made an unusual discovery when it comes to a member of an Asian group of fanged frogs. It turns out that the new species gives birth to live tadpoles rather than laying eggs.

The researchers actually stumbled on this discovery while slogging through the rainforests of Indonesia's Sulawesi Island one night. One of the scientists grabbed what he thought was a male frog; however, he soon found out how wrong he was. He wasn't only holding a female frog, but was also juggling dozens of slippery, newborn tadpoles.

"Almost all frogs in the world-more than 6,000 species-have external fertilization, where the male grips the female in amplexus and releases sperm as the eggs are released by the female," said Jim McGuire, the researcher who discovered the female frog, in a news release. "But there are lots of weird modifications to this standard mode of mating. This new frog is one of only 10 or 12 species that has involved internal fertilization, and of those, it is the only one that gives birth to tadpoles as opposed to froglets or laying fertilized eggs."

Frogs have evolved an amazing array of reproductive methods. Usually, though, male frogs fertilize eggs after the female lays them. Yet other species have evolved ways to fertilize eggs within the female's body. While internal fertilization is rare, though, there are other bizarre reproductive variations that frogs have evolved; some carry eggs in pouches on their back, and two known (and now extinct) species of female gastric brooding frogs were famous for swallowing their fertilized eggs and brooding them in their stomachs.

The new species of frog, though, seems to prefer to give birth to tadpoles in small pools or seeps located away from streams, possibly to avoid larger fanged frogs hanging out along the stream. There is even some evidence that the males may guard the tadpoles.

The findings are published in the journal PLOS One.

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