“Dark lime green” is how biologist Zachary Rodriguez describes the blood of the Prasinohaema lizards of New Guinea and surrounding islands. “Vivid,” he adds.
With green blood comes Granny Smith-colored muscles and bones and a blue-green mouth, exposed during defensive posturing. But the strangest thing about the five species of Prasinohaema lizard is that they can live like that.
Lime, apple and avocado can be risky blood colors. They indicate that these lizard species build up a toxic substance called biliverdin. The lizards’ red blood cells still depend on hemoglobin, the stuff that ferries oxygen and makes most animal blood red, but any lizard-blood redness is overwhelmed by massive concentrations of the green biliverdin. A breakdown product of hemoglobin, biliverdin gives the greenish edge to bruised human flesh. Most animal bodies quickly whisk it away.