Respiratory System

The cockroach's respiratory system is unusually well developed for a terrestrial insect and works independently of the blood. Ten pairs of small openings called spiracles (or stigmata), guarded by sphincter (spiracular) muscles that open and close them, sit along the sides of the body and lead into a network of branching tubes called tracheae. These divide further into fine terminal branches, the tracheoles, which deliver oxygen directly to individual tissues; each tracheole holds a small amount of watery fluid through which the actual gas exchange occurs, and during intense activity this fluid is drawn back into the tissues to speed up oxygen diffusion. Air therefore travels in the sequence spiracles to trachea to tracheoles to tissues. Because breathing happens through these body-wall openings rather than through the mouth, a cockroach can survive for about a week after losing it …