By the time they're adults, the frogs have turned a striking green, with blue-and-yellow striped sides, orange or red feet, a flash of blue on their thighs, and big red eyes. The bright colors are a defense mechanism. Being green helps the red-eyed tree frog blend in with tree leaves. If the green camouflage fails and a predator spots a sleeping frog, it swoops in for what it thinks will be a tasty meal. But the awakened frog's eyes pop open, revealing their startling bright red color! Also, when the frog rushes to get away, it untucks its brightly colored legs. The predator is often so surprised by these sudden flashes of color that it is momentarily confused and hesitates. And while it does, the frog has a split second to make its escape (nationalgeographic.com)!