EVERYDAY SCIENCE

Detailed explanation-1: -The spiracles can be opened and closed in an efficient manner to reduce water loss. This is done by contracting closer muscles surrounding the spiracle. In order to open, the muscle relaxes. The closer muscle is controlled by the central nervous system but can also react to localized chemical stimuli.

Detailed explanation-2: -The spiracles contain valves that can close in order to prevent water loss, although this also limits gas exchange. The tiny hairs surrounding the spiracles also help to trap humid air reducing the concentration gradient of water vapour which reduces water loss.

Detailed explanation-3: -To help reduce water loss, many insects have outer coverings to their tracheae, or spiracles, which shut when open respiration is unnecessary and prevent water from escaping.

Detailed explanation-4: -Instead of nostrils, insects breathe through openings in the thorax and abdomen called spiracles. Insects that are diapausing or non-mobile have low metabolic rates and need to take in less oxygen. Insects exchange oxygen and carbon dioxide through spiracles (noted by circle).

Detailed explanation-5: -In insects with a spiracle-closing mechanism, the rate of loss of water under the second two conditions (which caused them to keep their spiracles open permanently) was two to seven times that in dry air.