Hydra, one of the oldest organism to able to move on surfaces, A. stretches itself, B. holds substrate by the head with 5 arms, and C. then releases the base to stand inverted. The hydra is helped in this motion by a stiffness (elastic) gradient along its body column such that the head region is 25% stiffer than the rest of the body column. Now compare the relaxation of a real hydra with a computaional model of the same motion. Our model helps
explain how the stiffness gradient aids this somersault motion.
