AbstractThe water mites of standing waters have evolved a novel respiratory system consisting of numerous independent tracheae of tracheolar dimensions. Each trachea has a portion of its length lying directly under the cuticle and one or both ends of the trachea turn into the body to supply some organ. There is no fusion of tracheae to form trunks. Areas of dense tracheation dorsal to the legs supply the leg muscles, and sometimes there is a distinct area of the venter that supplies the muscles of the mouthparts.