The Chile Darwin’s frog is one of only two frogs in the world where the young undergo part of their development in the parent’s mouth. Eggs are laid on damp ground and, when the developing tadpoles start to wriggle in their egg capsules, the guarding male swallows them into his vocal sac. Here they stay until their jaws and digestive tracts are fully formed, where upon the male carried them to a stream. This species has not been seen since around 1980 and it could have been driven to extinction by a mystery disease, possibly the fungal disease chytridiomycosis (responsible for many amphibian declines globally), although this has not previously been reported from Chile.