Abstract: A pump having an elastic hose fixed at its two ends and a hose actuator for conveying fluid from the hose inlet to the hose outlet. The hose actuator comprises means for imparting to the free portion of the hose such a progressive transverse undulating movement about an element immovably provided within the hose along the entire length thereof, while sealing or approximately sealing the hose at two opposite points, that the hose at all times and with constant cross section engages or substantially engages the element at other points along the hose for closing said hose.