Meeting Abstract
Flies receive the accolade of being eminent fliers for their capabilities of performing precisely coordinated aerial manoeuvers. Landing upside down on the ceiling, for example, is arguably one of the most remarkable flight behaviors of flies when they execute a sequence of precisely- controlled body maneuvers to rapidly align its body with the ceiling under stringent time constraints. In this study, we recorded 58 successful landings of bluebottle flies (Calliphora vomitoria), 22 of which were accomplished through a sequence of body angular maneuvers, and the rest rely primarily on forelegs groping the ceiling and lifting bodies upwards. In the former, the angular maneuvers are dominated by variable combinations of body pitch or roll rotations. It is known that landing of flies is mainly guided by visual cues derived from the optical flow field. Previous studies show that the visual cues such as relative radial expansion rate (RREV) and angular velocity of the landing surface perceived by flies play important roles in triggering and control the landing manoeuvers. Our analysis suggests that RREV instead of landing surface angular velocity is most likely to be the visual cue that triggers the angular maneuver, similar to triggering mechanisms for the deceleration and leg extension found in previous studies on landings on vertical surfaces. Moreover, the strong correlations between the peak angular rate and the magnitude of preceding visual cues or body linear velocities indicate that the landing is precisely controlled by visual and/or mechanosensory cues. To generate the angular manoeuvers during landing, flies use bilaterally symmetric and asymmetric wing kinematic changes, such as fore/aft tilting of stroke plane, shifting the mean wing pitch angle and lateral tilt of stroke plane.
