Terrestrial limbless gait selection through friction modulation

Limbless locomotion is exhibited by a wide taxonomy of animals and has been observed in water, land, and even air. While broad principles underlying aquatic limbless locomotion have been articulated, a similar understanding for the terrestrial variety remain elusive. Here we show through a model snake how a variety of gaits resulting from both active 3D body deformations and interactions with heterogenous environments, can be all viewed as modulation of local frictional effects along the body. This simple perspective provides new understanding of how snakes and other limbless creatures may exploit their compliant body and naturally occurring substrate features to achieve adaptivity, control and gait selection.