Grainy Cochran Frog

Members of the Centrolenidae family are known as "glass frogs" because their abdominal skin is often translucent, allowing a close observer to see their internal organs at work. Cochranella granulosa, or the grainy Cochran frog—also known as the crystal frog—gets its name from the fine, particulate quality of its skin, which is tinted dark bluish-green with black spots.

Cochranella granulosa is arboreal, living in trees in the sticky, humid forests of South America. It keeps a decidedly low profile, and even when it’s out, it’s sooner heard than seen: males are known to emit a harsh and persistent creaking call to advertise themselves to potential mates, often calling as loudly as they can to drown out rival suitors. They can be belligerent as well, especially when it comes to defending an ideal streamside mating spot: territorial disputes—in which two males hang upside down from neighboring leaves and grapple chest to chest—can last up to two hours (and have been likened to sumo wrestling matches).

Like all glass frogs, the grainy Cochran frog is most active at night, which—along with their bodily transparency—makes it hard to spot for predators and sightseers alike. During daylight, it blends in easily with the flora of the rainforest, especially when flattened against leaves. Consequently, much of what we know about its behavior is based on times when it comes out to mate and breed.