Gas Exchange in Insects

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Gas Exchange in Insects

Insects, being larger and having a hard, chitinous and therefore impermeable exoskeleton, have a more specialised gas exchange system.

Insects have no transport system so gases need to be transported directly to the respiring tissues.

There are tiny holes called spiracles along the side of the insect.

spiracle

The spiracles are openings of small tubes running into the insect's body, the larger ones being called tracheae and the smaller ones being called tracheoles.

The ends of these tubes, which are in contact with individual cells, contain a small amount of fluid in which the gases are dissolved. The fluid is drawn into the muscle tissue during exercise. This increases the surface area of air in contact with the cells. Gases diffuse in through the spiracles and down the tracheae and tracheoles.

Ventilation movements of the body during exercise may help this diffusion.

The spiracles can be closed by valves and may be surrounded by tiny hairs. These help keep humidity around the opening, ensure there is a lower concentration gradient of water vapour, and so less is lost from the insect by evaporation.

Scarab beetle

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