The motion of limbless animals arises as the result of the interaction of their central nervous system, muscle and connective tissue, bone, and their environment. Two such important interactions are the highly elastic titin inside of muscle fiber and the damping that results from the interaction of muscle fibers during expansion and contraction. Prior work in the area of snake locomotion has imposed the kinematics of slithering and analyzed resulting motion. To gain an understanding of internal forces and stresses, we apply traveling waves of the moment to a non-linear visco-elastic beam model. Consistent with the friction properties of the scales of snakes and limbless lizards, environmental forces are modeled using anisotropic Coulomb friction. We find that by varying the crawler body’s internal stiffness, the crawler’s performance and direction can be altered. Further, we identify the parameters that produce optimally efficient gaits. We find that these parameters that produce optimal speed and efficiency are functions of the environmental friction. A better understanding of how these internal parameters affect locomotion can be employed in designing soft robotic platforms for surgery, search and rescue, and exploration.