Known as the hyalinobatrachium pellucidum (which means translucent skin), the glass frog, also referred to as the see-through frog, is part of the amphibian family Centrolenidae. About the size of a fingernail, the glass frog is native to Ecuador and the Amazonian slopes, but it also resides in many areas of Central and South America. Its most prominent feature is the transparent abdominal skin.
The earliest known report of the glass frog was recorded in 1872. By 1973 herpetologists John D. Lynch and William E. Duellman published a comprehensive paper further classifying the translucent amphibian. The field guide Zipcode Zoo indicates that the glass frog reproduces by laying eggs on vegetation that hangs over bodies of water with the tadpoles developing in streams. Some genus of glass frogs will lay eggs on rocks near waterfalls. While some frogs eat their young, some males are highly territorial and show parental care.
Centrolenidae, the amphibian family of the glass frogs, are primarily lime green. The heart, liver and intestinal tract, can be seen through the transparent abdominal skin. Glass frogs have webbed fingers and toes. The length of Centrolenidae frogs ranges from 1.2 inches to 3 inches. Their eyes face forward (unlike frogs with walled or outward facing eyes).
The glass frog is a freshwater creature that occupies tropical and subtropical forest territory and inland wetlands, including permanent rivers, streams, creeks and waterfalls.
In 2004 the International Union for Conservation of Nature and Natural Resources (IUCN) Red List declared hyalinobatrachium pellucidum as an endangered species. Fewer than 5,000 exist. The cause of threat is habitat loss due to small farmers and logging in the Amazonian slopes of the Ecuadorian Andes. IUCN recorded five specimens found in 1979 at Río Azuela in Ecuador. Even when assessors have revisited several times since then, they have found no other glass frogs.
The glass frog has been found in three river locations in the Napo province on the slopes of the Andes in the Amazon: Rio Azuela, Rio Reventador and Rio Salado.