Glass frog photographed during sleep and while active, showing the differences in red blood cells within the circulatory system. Jesse Delia via AMNH When a tiny glass frog dozes off to sleep, its ...

Dec. 23 (UPI) --Researchers say they have solved the mystery of how glass frogs become mostly transparent while they sleep. The discovery may lead to innovations in how to understand blood clotting.

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 ...

Glass frogs also have a unique circulatory system, with veins that are closer to the surface of the skin. This allows the oxygen-rich blood to be visible through the skin ...

MOST text-books of elementary zoology contain an account of the circulation of the frog. These accounts, which are based largely on the views of Brücke 1 and Sabatier 2, differ in minor details, but ...