Meeting Abstract
Storage of energy in elastic structures can overcome limits on muscle power production and allow small animals to achieve movements rivaling those of larger ones. Elastic structures recoil with greater power than muscles can generate, effectively amplifying muscle power. They can also confer thermal robustness to behaviors that must occur at different temperatures because muscle power production is reduced at lower temperatures, but the power of a recoiling elastic structure is not. To study the interaction of power amplification and thermal robustness from elastic recoil, we examined elastically powered jumping in Cuban tree frogs (Osteopilus septentrionalis). We recorded high-speed video and force plate data from the jumps of 25 frogs ranging from 2-42 g, at 10 and 30°C. We used inverse dynamics to calculate the energy released by each joint (hip, knee, ankle, tarsometatarsal) and related that to the total energy produced. Based on morphology, we assumed that energy released at the hip or knee came directly from muscle, whereas energy released at the ankle or tarsometatarsal joint was stored elastic energy. We found the proportions of energy coming from each hind limb joint did not change with size. Although the largest frogs could theoretically achieve observed jump performance using only muscle, they used similar amounts of elastic recoil compared with smaller frogs. We also expected the relative contributions of elastically powered joints (ankle and tarsometatarsal) to increase at lower temperatures, but these remained constant. Cuban tree frogs of all sizes use the same mechanism to achieve similar jump performance and are similarly affected by changing temperature.
