Meeting Abstract
An organism’s ecology, morphology, and motion are linked throughout evolution, each influencing and accommodating the others. In the bat Thyroptera tricolor, suction cups evolved at the bases of the thumbs and feet in connection with specialized roosts—the protective funnels of furled leaves—and allow these bats to adhere to and move along smooth leaf surfaces. Decades of research into the morphology of these suction discs, as well as ecological and behavioral studies, have failed to describe how T. tricolor uses these structures during locomotion. We investigated the biomechanics of landing maneuvers in this species. We measured 3D impact force and kinematics by training wild-caught bats to land on a force plate disguised as a furled leaf while recording the event using multi-camera high speed videography. Landing maneuvers comprised three phases: 1) positioning, 2) ballistic descent, and 3) adhesion. When positioning, bats adjusted their location and body orientation until they were in front of and above the leaf-tube manifold. Once positioned, bats folded both wings to passively descend into the leaf, keeping body orientation relatively constant and horizontal. Bats initiated adhesion to the leaf using both thumb-discs. These first points of attachment acted as fulcra about which the bat rotated to swing the foot-discs into contact with the landing plate. Peak 3D impact force was 7.67±2.84 bodyweights (n=50 landings). Compared to bat species with different roosting habits, including several that also roost on foliage, landings in this species employ a unique sequence of body rotations and enact higher peak impact force. We propose that the biomechanics of T. tricolor landing maneuvers are strongly influenced by their distinctive roosting ecology.
