Answer: Spiracles

Among air-breathing vertebrates like humans and other mammals, birds, and even reptiles, the process of respiration is one well familiar to us: we breathe in through our noses or mouths, air flows down into our lungs, and there—be it in a large set of horse lungs or a tiny set of hummingbird lungs—oxygen and carbon dioxide are exchanged.

But in insects, which have no lungs to speak of, the process of respiration looks completely different. A tiny ant doesn’t open its mouth and take in a deep breath, nor does a dragonfly huff-and-puff like it would if it was a fleet-footed mammalian predator. Instead, insects breathe through tiny openings in their exoskeletons called “spiracles”, which lead to a densely networked array of tubes under their exoskeletons called tracheae.

Unlike our trachea, however, a large single pathway that delivers oxygen down to our lungs, an insect’s tracheae branches throughout their body much like the bronchial tubes branch throughout our lungs. The elaborate tracheae network delivers oxygen directly to the insect’s cells as the insect has no blood-driven circulatory system, like we do, to perform the delivery and pickup work.