A father's throat pouch
In the temperate rainforests of Chile and Argentina lives a small amphibian with a reproductive strategy unknown in any other terrestrial vertebrate. The male Darwin's frog—named for Charles Darwin, who first discovered the southern species in 1834—takes on the primary parenting duties in a very direct way. The female lays a clutch of three to forty eggs on the moist forest floor and then leaves. The male guards the eggs for about three to four weeks. When he sees the larvae beginning to move inside, he ingests the eggs, pushing them into his vocal sac.
This vocal sac, normally used to attract mates, transforms into a nursery. The eggs hatch about three days later. Inside the sac, the tadpoles are protected from predators. They receive nourishment from their own egg yolks and from secretions produced by the wall of the sac. After 50 to 70 days, fully formed froglets, each just a few centimeters long, emerge from the male's mouth and hop away. This behavior, a form of mouthbrooding, is an extreme example of paternal care.