Meeting Abstract
Gliding evolved at least nine times in mammals. Despite the abundance and diversity of gliding mammals, little is known about their convergent morphology or mechanisms of aerodynamic control. Gliding animals are capable of impressive and agile aerial behaviors and their flight performance depends on the aerodynamic forces resulting from airflow interacting with a flexible, membranous wing (patagium). Although the mechanisms that gliders use to control dynamic flight are poorly understood, the shape of the gliding membrane (e.g., angle of attack, camber) is likely a primary factor governing the control of the interaction between aerodynamic forces and the animal’s body. We examined the structure and mechanical properties of the colugo gliding membrane to generate hypotheses for mechanisms of wing shape control. We used cross-polarized light to visualize and describe numerous intra-patagial muscles. Evenly spaced muscle fiber bundles that could be involved in tension control or membrane packing occur both in the propatagium and uropatagium, running both parallel and perpendicular to the free edge of the patagium. The membrane is under tension when it is outstretched, suggesting the presence of internal, organized elastic tissue. We discovered that membrane material properties vary by location and orientation. Based on measurements, the patagium is stiffer in the craniocaudal direction than along the mediolateral axis. Similarly, the membrane is both thicker and stiffer near the body than near the free edge of the patagium. Both the abundance of intra-patagial muscle fibers and material anisotropy have consequences for membrane shape and likely allow for the high level of aerodynamic control exhibited by these animals during glides.
