In "Science," the researchers reported that some frogs in South and Central America could become transparent on and off.
During the day, these frogs sleep, hanging under the leaves of trees. Their elegant, greenish-transparent forms cast no shadows, making them nearly invisible to birds and other predators. That type of frog is called the northern glass frog.
Glass frogs become opaque reddish-brown when they awaken and jump around looking for insects and mates.
