Department of Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Kiel, Germany
Sebastian is a PI at the department of ‘Functional Morphology and Biomechanics’ at Kiel University, Germany, funded by the ‘German Science Foundation’ (DFG). He is fascinated by the plethora of forms and functions arthropods have to offer and is focusing on the (multi-)functionality of their appendages. In this framework, Sebastian is working on predatory strikes of insects: functional eco-morphology, kinematics, biomechanics and biomimetics behind fast motions and grasping processes. Prior to this, Sebastian was post-doc at the Brigham Young University (BYU) in Provo, USA and the Zoological Institute at Cambridge University, Cambridge, UK. He did his doctorate at the University of Göttingen, Germany, where he also finished his biology degree.
Hunting with catapults: the predatory strike of dragonfly larvae
| Throughout all animal groups, predator-prey relationships can cause an evolutionary arms race, which can lead to the development of predatory as well as defence systems. The countless examples revealed elaborate biomechanical adaptions, some of which even improved technology. Adult dragonflies roam the air in summertime and are a delight to every naturalist. The offspring of these colourful flying insects, however, are alien-like aquatic predators. They catch their prey with a unique and highly efficient grasping apparatus derived from a strongly modified mouthpart – the so-called prehensile labial mask. In the present talk, firstly, the kinematics and biomechanics of this extensible mouthpart, which is thrust forward in a ballistic movement, will be presented. Secondly, a bio-inspired robotic arm, as a proof of concept, will be used to deepen our knowledge about the predatory strike. Finally, computational fluid dynamic simulations will be used to elaborate our understanding of such a high-speed movement under water. Here, a newly described independently loaded synchronised dual-catapult system is now hypothesised as the main driving mechanism of the predatory strike of dragonfly larvae. Two linked catapult systems, allowing for independent loading, are described. Both use a joint latch mechanism and one trigger muscle for synchronisation, resulting in a high-speed predatory strike that enables these aquatic key predators to successfully capture prey. However, such fast motion underwater usually meets a substantial problem – drag. A bow wave formation in front of the predator (or moving part of the predator) can alarm or even displace the prey item. Preliminary computational fluid dynamics results suggest the generation of a low-pressure zone above the distal segment of the prehensile labial mask that likely prevents the formation of a pressure wave in front of it. These results lead to the assumption, that a compensatory suction feeding-like effect (similar to what is known for aquatic vertebrates) helps to mitigate this problem. Finally, a proof of concept is presented: a 3D-printed robotic system inspired by the insect’s prehensile labial mask. Here, one of the great benefits of bio-inspired robotic systems becomes clear: one learn from nature to inspire technology but vice versa one can use this technology to learn about nature. |
