Gaps in our understanding of aerodynamic mechanisms across insects and vertebrates. Gaps in our understanding of aerodynamic mechanisms across insects and vertebrates. Vertically, we list seven aerodynamic mechanisms studied so far for flapping animal flight (the light green shading groups morphological effects as the seventh mechanism). Horizontally, we list animals (insects, bats, hummingbirds and other birds). White columns represent slow flight and light blue columns represent faster flight. Colored circles indicate the methodology used to study the aerodynamic mechanism. CFD, computational fluid dynamics. Filled and open circles indicate quantitative and qualitative studies, respectively. Note that filled circles do not imply direct force measurements, as many studies rely on force estimates based on flow field or kinematic measurements combined with theory. The corresponding references are provided in Tables S1 and S2. Diana D. Chin, and David Lentink J Exp Biol 2016;219:920-932 © 2016. Published by The Company of Biologists Ltd