The transport of oxygen and carbon dioxide into and out of organisms is also called respiration. In insects respiration is conducted by the trachael system. The main anatomical points are the paired spiracular openings leading into a series of tubes. The spiracles often feature elaborate opening and closing mechanisms that are physiologically controlled to regulate air flow and reduce water loss from the insect. There are fewer spiracles in some aquatic insects.
Some insects have a single pair of spiracles and a few small insect have no functional spiracles.
The trachael systems of many insect species also include relatively large air sacs. These air sacs can be compressed to force air into and out of the insect body. They sometimes also function in thermoregulation by insulating one body compartment from another. The trachael system is really a system of tubes. There are spiracles on either side of the body, leading into longitudinal trunks at the sides.