ASTLEY, H. C.**; LOCHETTO, S. M.; MOSKALIK, B.; JAYNE, B. C.; Univ. of Cincinnati; Univ. of Cincinnati; Univ. of Cincinnati; Univ. of Cincinnati: Climbing without limbs: Arboreal locomotion of snakes
Environmental variation commonly affects patterns of movement, muscle activity, and energetics of locomotion. Some of the functional challenges imposed by arboreal habitats include inclines, balancing, and fitting on surfaces of limited width which have been well studied for limbed vertebrates such as primates and lizards. Although several lineages of snakes have independently become specialized for arboreal habitats, data on the mechanisms and modes of arboreal locomotion of snakes are lacking. Thus, we videotaped five phylogenetically diverse species of snakes climbing on cylinders of varying diameter and incline to determine if perch attributes affect kinematics and performance within a species and if locomotor modes varied among species. Four species (Python reticulatus, Corallus hortulanus, Morelia spilota, Elaphe guttata) are obligate constrictors, and one species (Boiga irregularis) is mildly venomous and occasionally constricts prey. Corallus hortulanus and small individuals of B. irregularis are more attenuate and specialized for arboreal locomotion than the other species. We observed two major strategies for moving on cylindrical perches. B. irregularis perfomed a variant of lateral undulatory locomotion without grasping the perch, whereas the other species grasped the perch firmly during static contact while performing a variant of concertina locomotion. Species that grasped the perch varied in whether the body was wrapped helically or was looped alternately to the left and right. Quantitative differences among species included speed and forward progression per cycle of movement. Descent of steep inclines usually lacked the momentary static contact that occurred while ascending. Thus, despite the superficial similarity of an elongate limbless body plan, arboreal snakes displayed an unexpected diversity of locomotor modes.
