The color is a warning. Blue poison dart frogs with their many shades of blue, shot on OPPO Find X3 Pro. Photograph by Joel Sartore/National Geographic Surprisingly, blue is a rare color in nature ...

Curare [kyoo-RAW-ree], for example, is found on the skin of colorful poison dart frogs. Another special feature of most amphibians is their egg-larva-adult life cycle. The larvae are aquatic and ...