The biomechanics underlying the predatory strike of dragonfly larvae is not yet understood. Dragonfly larvae are aquatic ambush predators, capturing their prey with a strongly modified extensible mouthpart. The current theory of hydraulic pressure being the driving force of the predatory strike can be refuted by our manipulation experiments and reinterpretation of former studies. Here, we report evidence for an independently loaded synchronized dual-catapult system. To power the ballistic movement of a single specialized mouthpart, two independently loaded springs simultaneously release and actuate two separate joints in a kinematic chain. Energy for the movement is stored by straining an elastic structure at each joint and, possibly, the surrounding cuticle, which is preloaded by muscle contraction. As a proof of concept, we developed a bioinspired robotic model resembling the morphology and functional principle of the extensible mouthpart. Understanding the biomechanics of the independently loaded synchronized dual-catapult system found in dragonfly larvae can be used to control the extension direction and, thereby, thrust vector of a power-modulated robotic system.

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Presenting your research in the proper light can be exceptionally challenging. Meanwhile, dome illumination systems became a standard for micro-and macrophotography in taxonomy, morphology, systematics and especially important in natural history collections. However, proper illumination systems are either expensive and/or laborious to use. Nowadays, 3D-printing technology revolutionizes lab-life and will soon find its way into most people's everyday life. Consequently, fused deposition modelling printers become more and more available, with online services offering personalized printing options. Here, we present a 3D-printed, scalable, low-cost and modular LED illumination dome system for scientific micro-and macrophotography. We provide stereolithography ('.stl') files and print settings, as well as a complete list of necessary components required for the construction of three differently sized domes. Additionally, we included an optional iris diaphragm and a sliding table, to arrange the object of desire inside the dome. The dome can be easily scaled and modified by adding customized parts, allowing you to always present your research object in the best light.

Dragonfly larvae capture their prey with a strongly modified -extensible-mouthpart using 9 a biomechanically unique but not yet understood mechanism. The current opinion of hydraulic 10 pressure being the driving force of the predatory strike can be refuted by our manipulation 11 experiments and reinterpretation of former studies. On this fact, we present evidence for a 12 synchronized dual-catapult system powered by two spring-loaded catapults. The power output of the 13 system exceeds generally the maximum power achievable by musculature. Energy for the movement 14 is stored by straining a resilin-containing structure at each joint and possibly the surrounding cuticle 15 which is preloaded by muscle contraction. To achieve the precise timing required to catch fast-moving 16 prey, accessory structures are used to lock and actively trigger the system, ensuring the 17 synchronisation of both catapults. As a proof of concept, we developed a bio-inspired robotic arm 18 resembling the morphology and functional principle of the extensible mouthpart. Our study elucidates 19 the predatory strike of dragonfly larvae by proposing a novel mechanism, where two synchronized 20 catapults power the ballistic movement of prey capturing in dragonfly larvaea so-called 21 synchronized dual-catapult system. Understanding this complex biomechanical system may further 22 our understanding in related fields of bio inspired robotics and biomimetics. 24One Sentence Summary: The synchronized dual-catapult, a biomechanically novel 25 mechanism for the ballistic movement of prey capturing in dragonfly larvae 26 27 Keywords: biomechanics; functional morphology; catapult system; ballistic movement; 28 power modulation; robotic arm 29 42 Cicadomorpha; 4, 6). Here a catapult-like elastic mechanism is used to perform one of the fastest 43 jumps known by using chitinised cuticle as a spring (3). The elastic protein resilin rapidly returns the 44 leg to its original shape after a jump (using the jumps energy) and allows for repeated jumping (6). 45Resilin represents an essential element of high resilience, low fatigue, and damping mechanisms in 46 arthropods (12) due to its viscoelastic properties (13). In the specific case of a catapult system, the 47 near-perfect resilience (92-97%) and a fatigue limit of over 300 million cycles (14) in combination 48 with the ability to stretch to over three times its original length and recoil to its initial state without 49 plastic deformation (15,16) become important. 51Our example here, is the predatory strike Odonata (dragonflies and damselflies) larvae use to capture 52 preythey evolved a strongly modified, extensible mouthpart called prehensile labial mask ( Fig. 1A; 53 17,18). These larvae are key predators in their freshwater habitats, hunting invertebrates as well as 54 small vertebrates like tadpoles or fish from an ambush (19). These insects can project their specialised 55 mouthpart towards the prey, enabling the larvae to hunt effectively (see supplementary movie S1; 18). 56Previous investigati...