Reproduction in nature can be an odd thing (heck, so can human reproduction, for that matter), but some things are a given. For instance, since frogs are amphibians, it’s understood that they lay eggs that hatch, right? Well, according to a herpetologist from UC Berkeley, at least one species of frog breaks the mold – Limnonectes larvaepartus, a fanged frog in Indonesia, is believed to be the only species on Earth to give birth to live tadpoles.

Jim McGuire, the scientist that discovered the frogs, says it has to do with fertilization.

“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,” he said. “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 evolved internal fertilization, and of those, it is the only one that gives birth to tadpoles as opposed to froglets or laying fertilized eggs.”

While the newly discovered frogs are the only ones known to birth live tadpoles, they aren’t the only species to get creative with fertilization, gestation and birth. As McGuire mentioned, there are as many as 12 species that use internal fertilization – after that, things can get weird. Some females end up giving birth to froglets, tiny versions of adult frogs. Others nurse the tadpoles in their mouths or vocal sacs, or carry young tadpoles from place to place on their back.

Found on Indonesia’s Sulawesi Island, larvaepartus is just one of as many as 25 similar species on the island. The frogs vary widely in size, anywhere from a few ounces to two pounds, in some species. McGuire and his researchers noticed that larvaepartus prefers to birth and raise tadpoles in small pools rather than larger river. This is believed to be an effort to protect the tadpoles from larger fanged frog species.

“Sulawesi is an incredible place from the standpoint of species diversity endemic to the island as well as in situ diversification,” McGuire said.

L. larvaepartus was first discovered in 1998. It’s only the fourth fanged frog species on Sulawesi to be formally described.