Answer:
Respiratory movements are the muscular movement that helps in the entry or exit of air to and from the respiratory organs of an animal. The mechanism of the respiratory movement can be different in different animals.
In man, the respiration movements involve inspiration and expiration by the expansion and contraction of the thoracic cavity that leads to the flow of oxygen and carbon dioxide to and from the lungs.
In insects such as grasshopper, the flow of the air moves through the tracheae by rhythmic relaxation and contraction of abdominal muscles. In fish respiratory movements involves entering the oxygen through their mouth and release CO2 from the gills.