The Functional Morphology and Biomechanics of Arboreal Locomotion in Tetrapods: Leaping and Gliding in Arboreal Amphibians

Humans have been fascinated by amphibians that leap and glide from trees for centuries, possibly millennia. Here, I discuss aerial behavior and functional morphology along a gradient of arboreality to better understand the biomechanics of and adaptations for leaping and gliding in amphibians. Even nonarboreal frogs and toads experience short-term airborne flight after takeoff and reliably engage in aerial righting, forelimb-forward and controlled landing, and quick recovery that assist in terrestrial locomotion. However, arboreal amphibians are exposed to additional locomotor challenges, including long-term airborne flights, and subsequently exhibit more sophisticated aerial control. Gliding treefrogs have morphological features that maximize surface area and pressure drag and behavioral postures that enhance aerodynamic torque and maneuverability during flight. Likewise, some arboreal salamanders readily jump, albeit using entirely different biomechanics than anurans. The most arboreal species have flattened bodies, semi-webbed feet, and long limbs that provide high frontal area and pressure drag, enhancing maneuverability during flight. Although arboreal anurans and salamanders independently evolved to jump using completely different takeoff strategies, they seem to have converged upon similar functional morphologies and adaptive behaviors for gliding flight. The biomechanics of leaping and gliding in amphibians help inform our understanding of arboreal locomotion in tetrapods more generally.