How do insects breathe, and do they breathe at all? The body structure of the same beetles is significantly different from the anatomy of any mammal. However, these questions sometimes come up - for example, when a child puts a caught bug in a jar and asks how to provide him with a long, happy life.
So do they breathe, how is the breathing process carried out? Is it possible to close the jar tightly so that the bug does not run away, does it suffocate? These questions are asked by many people.
Oxygen, respiration and insect sizes
Modern insects are really small. But these are exclusively ancient creatures that appeared much earlier than warm-blooded, even earlier than dinosaurs. In those days, the conditions on the planet were completely different, the composition of the atmosphere was also different. It is even amazing how they managed to survive millions of years, adapt to all the changes that have passed during this time on the planet. The heyday of insects is behind, and in those days when they were at the peak of evolution, they could not be called small.
Interesting fact: the fossilized remains of dragonflies prove that in the past they reached half a meter in size. During the heyday of insects, there were other exceptionally large species.
In the modern world, insects cannot reach such sizes, and the largest are tropical individuals - a humid, hot climate saturated with oxygen gives them more opportunities for prosperity.Literally all researchers are convinced that it is their respiratory system with its specific device features that does not allow insects to thrive on the planet in today's conditions, as it was in the past.
Insect respiratory system
When classifying insects, they are classified as a subtype of tracheal breathing. This already answers many questions. Firstly, they breathe, and secondly, they do this through the trachea. Arthropods are also classified as gill-breathing and cheliceric, the former include crayfish, and the latter are ticks and scorpions. However, back to the tracheal system, characteristic of beetles, butterflies, dragonflies. Their tracheal system is extremely complex, evolution has polished it for more than one million years. Tracheas are divided into numerous tubes, each tube goes to a specific part of the body - much like blood vessels and capillaries of more advanced warm-blooded, and even reptiles, diverge across the body.
Tracheas are filled with air, but this is not done at the expense of the nostrils or the oral cavity, as in vertebrates. Tracheas are filled with spiracles; these are numerous holes that are on the body of the insect. Special valves are responsible for air exchange, filling these holes with air, and closing them. Each spiracle is supplied with three branches of the trachea, among which:
- Ventral for the nervous system and muscles of the abdomen,
- Dorsal for the dorsal muscles and the dorsal vessel, which is filled with hemolymph,
- Visceral, which works on the reproductive and digestive organs.
Tracheas at their end turn into tracheoles - very thin tubes that braid every cell of the body of the insect, providing it with an influx of oxygen. Tracheola thickness does not exceed 1 micrometer. This is how the respiratory system of the insect is arranged, due to which oxygen can circulate in its body, reaching each cell.
But such a primitive device has only crawling or low flying insects. Flying, such as bees, also have air sacs like those of birds in addition to lungs. They are located along the tracheal trunks; during flight, they are able to contract and swell again to provide maximum airflow to each of the cells. In addition, aquatic insects have air storage systems on the body or under the abdomen in the form of bubbles - this is true for swimming beetles, silverfish, and others.
How do insect larvae breathe?
Most larvae are born with spiracles, this is important primarily for insects living on the surface of the earth. Aquatic larvae have a kind of gills that allow them to breathe under water. Tracheal gills can be located both on the surface of the body and inside it - even in the intestine. In addition, many larvae are able to receive oxygen throughout the surface of their body.
Pupae also have tracheas, even aquatic individuals use them, rising to the surface of the water and sucking air through the tube, as mosquitoes do. Parasitic insects, on the other hand, during all the "childhood" stages breathe mainly on the surface of the body.
The modern atmosphere is probably not so rich in oxygen to allow insects to grow to large sizes. But in the past, when the continents were covered with dense tropical vegetation, even such a primitive system was effective, provided the growth, development and prosperity of this class of living creatures.
