Which frog carries its tadpoles in its vocal sacs?

Darwin’s frog is the frog that carries its tadpoles inside its vocal sac. After the female lays eggs on land, the male guards them until the embryos begin moving; he then takes the developing young into his mouth and transfers them into the vocal sac.

The tadpoles remain there while they develop, nourished by their yolk reserves and secretions from the sac’s lining. Eventually, miniature froglets emerge through the father’s mouth. This unusual form of paternal care is one of the most distinctive reproductive adaptations known among frogs.

The species is Rhinoderma darwinii, the southern Darwin’s frog. Charles Darwin encountered it during the voyage of HMS Beagle in Chile, and it was formally described in 1841. Its pointed, leaf-like snout helps it blend into the forest-floor litter of southern Chile and neighboring Argentina.

A related species, the Chile Darwin’s frog, Rhinoderma rufum, has a similar mouth-brooding strategy but is generally considered extinct or possibly critically close to extinction. Ordinary bullfrogs, tree frogs, and poison dart frogs may carry eggs or tadpoles in other ways, but they do not use the male vocal sac as a complete tadpole nursery.