Meeting Abstract

80.5  Wednesday, Jan. 6  Comparative gliding performance in wingless gliding ants and other arthropods MUNK, Y; UC Berkeley

Many wingless insects are capable of sophisticated aerodynamic control in the absence of obvious morphological adaptations for aerial behavior. We present comparative data on aerial maneuvers in worker ants, focusing on the genus Cephalotes, and in other wingless arthropods, including the basal hexapod lineage of wingless jumping bristletails (Archaeognatha). In all gliding ants tested to date, aerodynamic stability and control are effected through modulation of leg posture, with the legs raised above the longitudinal body axis to maintain a center of aerodynamic pressure above the center of mass. Typically the hindlegs move together as a unit and serve to adjust overall body pitch angle. In contrast, the mid- and forelegs are actuated asymmetrically to effect yaw and roll maneuvers. In some cases the antennae are also co-opted as aerodynamic stabilizers. All Myrmicine (including the genus Cephalotes) and Pseudomyrmecine ants tested to date glide with the abdomen leading, whereas all tested Formicines adopt a head-first gliding posture. In contrast to these ants and other wingless gliding arthropods, bristletails appear to execute maneuvers by adjusting the position of their long caudal filaments through abdominal flexion. We present 3D trajectories of ants performing targeted and controlled directed aerial descent in a natural Amazonian setting, measured using a tree-based synchronized camera array. We also compare gliding postures adopted by ant species of varying body size, obtained using a field-portable open-jet wind tunnel. Finally, we will present the first results from an ongoing series of physical modeling experiments designed to quantitatively assess how morphology and posture affect net aerodynamic forces and moments acting on gliding insects.