The astonishing vanishing act of the glassfrog, revealed

https://www.npr.org/2022/12/26/ [login to see] /glassfrog-hides-its-blood-glass-frogs
Jesse Delia says it happened in Panama. A few years back, he was finishing up his field work — a research project examining the parental behavior of a type of glassfrog. He brought a handful of these transparent, half dollar-sized frogs to the lab for a photo shoot.

It led to an exciting discovery.

"I wanted to get some photos of a pretty glassfrog belly," Delia tells NPR. He placed them in a Petri dish and saw each frog's circulatory system through its translucent skin — "red with red blood cells."