If you’ve ever wanted to peer inside an animal without harming it, the glass frog offers an amazing opportunity. These tropical frogs have transparent skin on their undersides, making their organs visible. Their backs and the rest of their bodies are usually different shades of green. According to the University of Michigan Museum of Zoology, there are over 100 species.
Glass frogs live in the rain forests of Central and South America, and adults live in the trees. Most species are quite small, ranging between one to three inches in length. They tend to be active at night and many have green bones. Scientists aren't sure of their precise diet, but it's thought that glass frogs eat insects, similarly to other tree frogs.
New species of glass frogs are regularly being described by researchers. This past summer, scientists identified four new species in Peru.
The eggs of many glass frog species are also transparent. They lay their eggs in small clutches, on leaves that overhang water. This way, as the tadpoles hatch, they can slide into the water. Males often guard the eggs, defending them from predatory insects with their hind legs. You can watch an adult frog defending eggs (set to highly dramatic music) here.
Like too many creatures that live in the rainforest, glass frogs face habitat loss. The World Conservation Union has added several species to its list of “Vulnerable” animals, including the Cochran frog (Nymphargus cochranae) and the Pacific Giant Glass Frog (Centrolene geckoideum).