A hinged jumping appendage helps terrestrial springtails direct their ultrafast jumps

Many biological organisms (i.e., frogs, grasshoppers, and gall midges) use spring-latch mechanisms to generate ultrafast jumps and escape from potential predators. Directional control during escape jumps is important to effectively evade predators; however, in spring-latch systems, the ultrafast release of elastic energy can make energy flow difficult to control. Springtails (Collembola) are a group of non-insect hexapods that use a spring-latch jumping appendage called a furca to launch themselves off substrates at millisecond timescales. Here we look at whether terrestrial springtails have directional control over their spring-driven jumps. Using high speed video, we analyzed the takeoff kinematics of a terrestrial springtail ( Tomoceridae) leaping off of rigid substrates. Our experiments reveal a hinge in the springtail’s furca that help the springtail orient its ground reaction forces and gain forward momentum. Confocal microscopy of the furca shows that the hinge is a highly elastic structure that may passively absorb and release elastic energy at the millisecond time scale. Using mathematical modeling, we explore how the hinge affects the springtail’s jump and whether the hinge is necessary to orient ground reaction forces. Our findings offer novel insights into how ultrafast biological systems control their jumps and inform potential constraints on the flow of elastic energy through materials at millisecond timescales.