At rest they store almost 90 percent of their red blood cells in their liver, becoming more transparent.
Photo: Geoff Gallice from Gainesville, FL, USA · CC BY 2.0 · Original
89%of red blood cells end up in the liver
The story behind it
Sleeping glass frogs hide almost 90 percent of their red blood cells in their liver.
Red blood cells absorb green light and would give the frogs away on a leaf. So at rest they pack them into their mirror-like liver – and become two to three times more transparent. Why the blood doesn't clot is still unknown.