Self-propelling beach animals like Animaris Percipiere have a stomach . This consists of recycled plastic bottles containing air that can be pumped up to a high pressure by the wind. This is done using a variety of bicycle pump, needless to say of plastic tubing. Several of these little pumps are driven by wings up at the front of the animal that flap in the breeze. It takes a few hours, but then the bottles are full. They contain a supply of potential wind. Take off the cap and the wind will emerge from the bottle at high speed. The trick is to get that untamed wind under control and use it to move the animal. For this, muscles are required. Beach animals have pushing muscles which get longer when told to do so. These consist of a tube containing another that is able to move in and out. There is a rubber ring on the end of the inner tube so that this acts as a piston. When the air runs from the bottles through a small pipe in the tube it pushes the piston outwards and the muscle lengthens. The beach animal's muscle can best be likened to a bone that gets longer. Muscles can open taps to activate other muscles that open other taps, and so on. This creates control centres that can be compared to brains.