Here's how frogs usually grow: Gooey clutches of frog eggs (a familiar site in ponds across the world) hatch into tadpoles, which metamorphose into frogs. But not all frogs follow these steps, it turns out. As researchers just discovered, one frog from Indonesia skips the eggs and gives birth directly to live tadpoles.
Limnonectes larvaepartus, the frog in question, lives on the island of Sulawesi. It's a type of fanged frog—which have two fang-like protrusions on the lower jaw, that are used for fighting, as the BBC describes. Herpetologists had never studied this particular species in detail, until a team from the University of California, Berkeley, recently visited Sulawesi and collected some of the frogs.
The scientists were shocked when one of their captured frogs started to expel live tadpoles.
Herpetologists believe that up to 25 frog species that are similar to L. larvaepartus live on Sulawesi. So it very well could be that L. larvaepartus isn't the only frog to give birth to live tadpoles. But, of the 6,000 species of frogs described around the world, the BBC writes, only about a dozen are known to use internal rather than external fertilization. And all of those frogs, give birth to tiny, but fully formed live froglets rather than tadpoles.
Like many frogs across the world, many of these exceptional species are also threatened with extinction due to climate change, development and disease, according to the BBC. In fact, two species of frogs famous for swallowing their externally fertilized eggs and brooding them in their stomachs have already gone extinct, the researchers report.