How do insects breathe?
Most living things take in oxygen and give out waste carbon dioxide. This is what we do when we breathe. But all living things do not breathe through lungs and noses as we do. A tree uses tiny pores in its leaves, a fish uses gills and a worm breathes through his skin. An insect us s oxygen, but he has no lungs and no nose.
The air you breathe in, goes down to your spongy lungs. There the air touches tiny blood vessels, The red cells in the blood take out the oxygen from the air and tote it all around the body, Insects do not use a blood stream to carry their life giving oxygen around their bodies.
Most insects have a breathing system like the grasshopper's. You can examine this sizable insect with a magnifying glass and see part of his breathing system. His insect body, of course, is in three parts. He has a head and a chest, which is called a thorax, The thorax is joined to his third section, the abdomen, by a thick waist.
You would never guess where to look for his nose. In fact, he has no nose like yours, though you might say he has nostrils. The nostrils are tiny pore holes called spiracles and, of all places, you will find them along the sides of his abdomen and thorax. If you look closely, you may be able to count more than ten pairs of these tiny spiracles.
Each tiny spiracle is guarded with fine hairs to keep out the dirt. It is also fitted with a tiny valve which can be closed. Sometimes the air is very dry and tends to steal moisture from inside the grasshopper, He can close all his spiracles to keep out the dry air. He can open some spiracles to let fresh air Into his body and others to let out the waste air.
The spiracles lead into miniature air tubes. These tubes divide into finer and finer branches. They wander all through the inside of the insects body, touching every living cell. Here and there they empty into little pockets called air sacs. The insect can squeeze the air sacs open and shut. This pushes and hurries the circulation ~of air through the network of tubes. The cells grab oxygen from the fresh air and give out waste carbon dioxide. The used air finally reaches the spiracles again and seeps outside.
In the body of an insect, the air system is quite separate from the blood system. In a larger animal, the pumping heart and pulsing blood stream can carry oxygen a long distance. The sample breathing system of the insect can carry air only a very short distance. This limited breathing system is one reason why the insects never became large animals.