Elizabeth PennisiWhat color makes tree frogs so vibrantly green? The blue beneath their skin, of course. Those are the findings of a new study, which reveal that a unique protein complex that reflects blue light is responsible for an unusual green—helping them blend in to their surroundings and evade predators.Scientists came across the complex while trying to understand how hundreds of tree frog species can accumulate large amounts of a toxic green pigment known as biliverdin.
In most animals, biliverdin is so dangerous that it is immediately broken down or excreted. In humans, it forms when red blood cells break down and causes the greenish color sometimes seen in bruises.