Glass frogs can turn much of their body see-through while they sleep by pulling almost all of their red blood cells out of circulation and storing them in their liver, then releasing them again when they wake and need to move.

Glass frogs become much harder to see while they sleep, and they do it by getting their blood out of the way. While resting, the frogs pull roughly 89 per cent of their red blood cells out of circulation and pack them into the liver, which makes them two to three times more transparent. When [...] The post Glass frogs can turn much of their body see-through while they sleep by pulling almost all of their red blood cells out of circulation and storing them in their liver, then releasing them agai