The predatory strike of Odonata larvae – A temperature dependent spring actuated system

The larvae of Odonata are limnic predators capable of catching their prey using a highly modified mouthpart - the labium. Driven by a unique dual catapult mechanism, the apparatus can reach peak accelerations of up to 114.5m/s2. Yet little is known about the kinematics of the predatory strike in an ecological context. Here we show how different ambient temperatures affect the predatory strike and the avoidance reaction of prey items of Odonata larvae. We found that the extension velocity of the labial mask decreases significantly with the ambient temperature both in dragonflies and damselflies. However, temperature has lesser impact on the predatory strike itself than on directly muscle driven movements in both the predator and prey items. This contradicts the previous assumption that catapult mechanisms in insects are unaffected by temperature. Our results indicate that the prehensile labial mask is driven by a series-elastic catapult; a mechanism similar to the temperature dependent jump of frogs, where muscle and spring action are tightly linked. Our study provides novel insights into the predatory strike of Odonata larvae and offers a new ecological perspective on catapult mechanisms in arthropods in general.