How Parachute Frogs Took to the Sky

The jungles of East Asia are home to a few frog species. A glide can cover more than 50 feet.

Frogs lack the true wings of birds and bats, but they use their feet as a winglike surface to slow their descent. They have large feet, as well as flaps of skin on their limbs, and sticky toe pads to help them land safely.

University of Texas at Austin evolutionary biologist David Hillis and his colleagues at China's Chengdu Institute of Biology collected several specimen of black-webbed tree frog from rain forests in southern China.

The researchers compared the tree frog's genome with that of a closely related frog that couldn't glide. 455 modified genes were pinpointed for a study. Many of the genes we identified are related to foot and limb development. They are all consistent with the flying frog's gliding behavior. Long limbs and stickier toe pads were found by the researchers. The network of genes likely responsible for extra webbing was found by tracking foot development in tadpoles.

The researchers conducted a flight test to see the differences in action. Frogs were placed on perches and recorded any jumps and subsequent glides, as well as being placed under soft sponges to make sure they didn't fall. The nongliding frog fell into the sponges. The parachute frog played with their webbed toes as they glided down.

The extra webbing slows their fall and helps them steer through the rain-forest canopy, according to a biomechanist who was not involved in the work. The frog dodges trees by using large back feet as they descend toward puddles on the forest floor to mate and lay eggs. They will miss the orgy if they can't maneuver through this complex environment.

Understanding the frog's adaptation may help illuminate how other animals took to the sky. Frogs are used to help model dinosaurs. She says that flying dinosaurs had feathers on their legs. They had the same design as flies.