Insect respiration

Insect respiration is gas exchange through openings called spiracles and a branching tracheal system that carries oxygen toward tissues and removes carbon dioxide.

Spiracle: An external opening in an insect’s body that connects to the tracheal system. Spiracles admit air and can close to limit water loss.
Insect anatomy: The structure and organization of an insect’s body and its systems. Spiracles and tracheae are arranged across the insect body wall and internal tissues.
Insect flight: Powered aerial locomotion by insects, generated through movements of the wings. Flight raises oxygen demand, and some flying insects ventilate their tracheal systems actively.
Lung: A respiratory organ in which gas exchange occurs between air and blood or another circulating fluid. Unlike lungs, insect tracheae deliver air close to tissues rather than relying on blood to carry most oxygen.
Tracheal system: A branching network of air-filled tubes that delivers gases directly to insect tissues. Its branches carry oxygen inward and carbon dioxide outward.
Trachea: A tube that conducts air through a respiratory system; in insects, part of the tracheal network. Insect tracheae form the larger airways that branch into tracheoles.
Aquatic insect: An insect that lives in water for part or all of its life cycle. Aquatic species use adaptations such as air stores, respiratory surfaces, or plant-mediated gas exchange.
Gill: A respiratory organ that extracts dissolved gases from water across a thin surface. Aquatic insects may use gills, contrasting with the air-filled tracheal routes typical of terrestrial insects.
Tracheole: A fine terminal branch of an insect trachea that approaches or enters tissues. Gas exchange with cells occurs across the tracheoles’ thin endings.
Air sac: An expandable enlargement of an insect trachea that contains air. Air sacs can increase internal air storage and assist ventilation.

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