Spiracles

The distribution of spiracles can vary greatly among the many orders of insects, but in general each segment of the body can have only one pair of spiracles, each of which connects to an atrium and has a relatively large tracheal tube behind it.

Larvae breathe through spiracles located on their eighth abdominal segments, or through a siphon, so must come to the surface frequently.

The bubble covers at least some of the spiracles, thereby permitting the oxygen to enter the tracheae.

The front eight segments have spiracles and the terminal segment is modified for reproduction.

The front two segments have a pair of spiracles which are used in respiration.

The physical properties of the interface between the trapped air film and surrounding water allow gas exchange through the spiracles, almost as if the insect were in atmospheric air.

They have fifteen segments and spiracles in each segment for breathing.

Those that are able to breathe while not swimming do so by using their spiracles to force water over their gills, thereby allowing them to extract oxygen from the water.

Though all but the most primitive bony fish lack spiracles, the pseudobranch associated with them often remains, being located at the base of the operculum.