A fluidic muscle is a pneumatic or hydraulic actuator, consisting of a flexible tube. When the tube is filled with a working fluid (pressurized air or hydraulic oil), it balloons out and shortens. In some applications, fluidic muscles are superior to pistons.
In theory, you could imagine the same principle in reverse as a pump: Water flows into the tube under gravity, ballooning it out. The tube is then pulled apart, reducing its volume and ejecting the water. Check valves ensure proper water flow. Tbh, I don't see any advantage over other diaphragm pumps, but I could be wrong of course.