Meeting Abstract
Biological terrestrial locomotors navigate through a wide range of terrain, from tall grasses to forest floors to the yielding sandy substrates of the desert. These movements result from the coupling of environmental interactions with cyclic self-deformation patterns generated by animals. In animal movement on and within granular media, body inertial effects are small compared to dissipation; further, granular Resistive Force Theory provides an accurate model of these highly damped interactions. These features, along with a low-dimensional representation of self-deformation patterns, allow for the application of a general locomotion framework, geometric mechanics, which was introduced by particle physicists in the 1980’s to study swimming microorganisms. Recent advances in the theory have enabled application of this framework to continuous and hybrid systems and thus allow systematic comparison of body coordination patterns and morphology for locomotion of limbless and limbed animals. We find that undulatory snakes and lizards swimming within granular media use waveforms predicted to produce near-maximal displacements per undulation cycle. We find that the coordination between foot placement and spinal flexion observed in salamanders walking on the surface of granular media produces near-maximal displacements per gait cycle. These results highlight the broad applicability of these tools to understand coordination and self-deformation patterns in dissipative environments. We posit that movement on and within other dissipative environments (e.g., muds and leaf litter) could be amenable to these tools.
