The glass frog belong to the amphibian family Centrolenidae (order Anura). While the general background coloration of most glass frogs is primarily lime green, the abdominal skin of some members of this family is transparent and translucent. The internal viscera, including the heart, liver, and gastrointestinal tract, are visible through the skin, giving the glass frog its common name. Their transparency becomes jeopardized once on land however, and they are considered more translucent than truly transparent. Glass frogs are arboreal, meaning they mainly live in trees, and only come out for mating season. (Source: Wikipedia.org, CC BY-SA)