Masayuki Sumida and colleague at the Hiroshima University, Japan, had created a frog with transparent skin!
The researchers say the see-through frogs can help in the study of diseases and in the development of medical treatments by allowing laboratory scientists to check the status of internal organs and blood vessels while the frogs are alive and without having to dissect them.
According to Sumida, the transparent frog is the result of breeding two specimens of Japanese brown frog (Rana japonica) that had a genetic mutation giving them pale skin. By selectively breeding their offspring, the researchers were able to create a frog that remains transparent for its entire life cycle. Most of the world’s known transparent creatures live underwater, and transparent four-legged animals are extremely rare.
Link - Thanks Andrew!