Meeting Abstract
While a life in running water guaranties a constant supply with food, nutrients and oxygen, the physical features of this current shaped environment can be challenging. Stream insects have developed both, behavioral and morphological strategies to deal with flow forces. The mayfly larva Ecdyonurus sp. crawls to current exposed places to graze on algae on top of stones. Their dorso-ventrally flattened body shape is often considered to be an adaptation to flow forces. However, while this shape reduces drag, the same body shape increases lift. The later puts the larvae in danger of being detached from the bottom substrate. We used microscopic techniques, 3D-printing, and force measurements in a wind tunnel to investigate the role of the widened femora of Ecdyonurus sp. larvae in counterbalancing these lift forces. Our results show that the larvae use their femora like spoilers generating a downwards directed force (negative lift), which helps them to stay on the ground. The larva can actively regulate the amount of lift by changing the femur’s angle of attack. Depending on the specific conditions these stream insects can even use the ground effect to support the generation of negative lift.
