Meeting Abstract
Many snakes use their musculature to constrict and kill prey by exerting forces that the prey experience as pressures. Previous work has shown that snake-eating snakes (kingsnakes; Lampropeltis) produce higher constriction pressures than similarly sized intraguild competitors (ratsnakes; Pantherophis). Although kingsnakes produce higher constriction pressures than their ratsnake prey, there are currently no identifiable differences in their muscle anatomy. Because of their similar anatomy, previous work has suggested that differences in performance may be driven more by posture than by muscle performance. However, quantitative analysis of muscle performance is still needed. We investigated muscle physiology by quantifying in vivo muscle force and endurance in two epaxial muscles of kingsnakes (L. holbrooki;N = 8) and ratsnakes (P. obsoletus;N=8) to test for potentially superior muscle performance in kingsnakes. The semispinalis–spinalis and longissimus dorsi muscles from larger snakes produced higher forces (0.23–1.35 N), but there was no significant difference in max force between muscles or species. In endurance tests, all muscles lost 25% of their max force in an average of 58 s, and muscle force was reduced to an average of 38% of the max over a 4 min stimulation. There was no significant relationship between body size and endurance, and there was no difference in endurance between muscles or species. These and previous results indicate that kingsnakes are superior constrictors that can prey upon other large constrictors not because they have superior muscle performance, but because they use a more consistent and effective coil posture.
