What is the primary function of spiracles in insects?

The primary function of spiracles in insects is respiration. Spiracles are small openings located on the sides of an insect's body that lead to the tracheal system, a network of tubes that transport air directly to the tissues and organs. This adaptation allows insects to efficiently exchange gases, such as oxygen and carbon dioxide, without the need for lungs.

Insects rely on this system because they have a relatively high surface area-to-volume ratio, making direct air supply through spiracles advantageous for their size. The spiracles can open and close to regulate gas exchange and minimize water loss, which is crucial for their survival in various environments. While digestion, reproduction, and circulation involve other biological systems and structures, the spiracles are specifically adapted for functionally supporting the respiratory requirements of insects.