The task of producing steady, stable and energy efficient locomotion in legged robots with the ability to walk in unknown terrain have for many years been a big challenge in robotics. This work is focusing on how different robots build from the modular robotic system, LocoKit by Larsen et al. [1], performs compared to animals, and also on the similarities between robots an animals. This work shows, that there in robots exist the same connection between cost of transport and the weight of the robots as is true for animals.