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How Insect Breathe
Insects lack
lungs. Their basic respiratory system is tracheas. Tracheas of
insects are aeriferous tubes which end on the sides of the body
as small breathing holes (spiracles). Fine-branched parts of
tracheae — tracheoles — permeate the entire body, covering
organs and even penetrating inside some cells. In this way,
oxygen is delivered to the cells of the body, and the gas
exchange is ensured without use of the circulatory system.
Many insects
living in water (water beetles and true bugs, larvae and pupae
of mosquitoes, etc) have to rise to the surface to take in air,
i.e. they also have air breathing. Larvae of mosquitoes and some
other insects, for the time of renewing the air in the tracheal
system, get “hanged” from beneath to the surface of the water
with the help of water-resistant hairs.
Water beetles
(water scavenger beetles, true water beetles) and true bugs (for
example, backswimmers), having breathed at the surface, take on
an additional supply of air under their wing covers before they
submerge.
In larvae of
insects living in water, damp soil, tissues of plants, skin
breathing plays a big role.
Well-adapted to water life, larvae of mayflies, caddisflies, and
other insects have no open spiracles. They take in oxygen
through the surface of all parts of the body where the covering
is thin enough, especially through the surface of leaf-shaped
outgrowths permeated by a network of tracheas. Larvae of the
midge Chironomus also have respiration through the skin —
through the whole surface of the body.
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