Darwin's Frog (Rhinoderma darwinii) is a frog native to the forest streams of Argentina and Chile. It was first described by French Zoologist André Marie Constant Duméril and his assistant Gabriel Bibron, and is named after Charles Darwin who discovered it on his world voyage, "Voyage of the Beagle", on the HMS Beagle. The most striking feature is the way the tadpoles are raised—inside the vocal sac of the male. The female lays about 30 eggs and then the male guards them for about two weeks, until they hatch. Then the male takes all the survivors and carries around the developing young in his vocal pouch. The tadpoles develop in their baggy chin skin, feeding off their egg yolk. When the tiny tadpoles have developed (about half an inch) they hop out and swim away.

The frog is brown or green with a size of 2.5–3.5 cm. Its front feet are not webbed, but some of the toes on the back feet usually are. It eats insects and other arthropods. Darwin's frog not only has to hunt, but also must hide from predators wanting to eat it. Its most reliable technique to avoid its hunter is camouflage. It lies on the ground looking like a dead leaf until the predator passes by.