Introduction Understanding the relationship between form and function in organisms can increase our knowledge about natural processes, especially when it comes to investigating how physical laws apply to the adaptive design of organisms. The mode of locomotion plays a major role in the evolution of many body traits. Most terrestrial organisms walk or run upright on horizontal surfaces. Organisms that climb on vertical surfaces or hang from objects most likely evolved, through natural selection, specialized modes of locomotion to optimize ease and rate of movement.

In order to move, animals need to "build up" energy and then use that energy in a controlled way. One way to do that is through the interchange of kinetic and gravitational potential energy. One method to do this is an animal moving forward over a stiffened leg. In the initial part of the cycle, some of the kinetic energy used to propel the animal forward also raises its center of mass, increasing its gravitational potential energy. As the center of mass falls, gravitational potential energy is converted back into kinetic energy which facilitates the next step. This is called the inverted pendulum model (Figure 1).

What specific and measurable hypotheses (at least two) can you develop that are supported by the information presented and that address the basic question of this study?