The respiratory system of insects is the most accurate reflection of their lifestyle. Since these creatures are always above the ground, they breathe solely due to the trachea, which they have much more developed than other inhabitants of our planet. In fairness, it is worth highlighting that there are some superclasses of insects that live in the aquatic environment, or often go there. In this case, the respiratory system of insects is represented by gills. However, these are extremely rare species of this class, therefore we will examine them also very briefly. Well, let's move on to a more detailed study of this section of biology.
general information
So, the respiratory system in insects appears to us in the form of trachea. From them emanate numerous branches that spread throughout all the vital organs and systems of the body. The whole body, with the exception of the head (that is, the thoracic region and abdomen) is covered with exit openings - spiracles. They form the tracheal system, thanks to which most insects can breathe through the surface of their body.
It should be noted that these spiracles are reliably protected from environmental stimuli by special valves. They respond quickly to air intake thanks to well-developed muscles. It is also important to know that the spiracles are on the sides of each segment of the body. The size of their holes is regulated, due to which the tracheal lumen changes.
Ventilation process
In order to understand thoroughly how insects breathe, it is important to first understand that every tracheal system located in the body is always ventilated. The necessary air exchange occurs due to the fact that the valves that are located along the body, roughly speaking, open and close according to a certain schedule, that is, coordinated. For example, consider how a similar process occurs in locusts. During the air inlet, the anterior 4 spiracles open (among them are two chest and two ventral anterior). At this time, all the rest (6 rear) are in the closed position. After air has entered the body, all spiracles are closed, and then the opening occurs in the following sequence: 6 rear open, and 4 front remain closed.
Major respiratory movements
Many years ago, scientists, considering how insects breathe, noticed that their bodies are compressed and unclenched in a certain way. This process turned out to be synchronous with the process of oxygen ingestion into the body, and therefore it was concluded that many representatives of arthropods breathe precisely due to standard mechanical actions. Thus, the respiratory system in insects can function due to contractions of individual sections of the abdomen. This type of "breathing" is characteristic mainly of all terrestrial creatures. Those individuals who live partially or completely in water are characterized by a reduction in some of the thoracic regions. It is also important to remember that it is the contraction of muscles that occurs during expiration. When air enters the body, all the abdominal and thoracic segments of the insect, on the contrary, expand and completely relax.
The structure of the trachea
It is the trachea, as mentioned above, that the respiratory system of insects is represented. For children, such a concept may turn out to be too complicated, because if you explain this biological process to your child, then tell him first how this respiratory organ looks like. In almost all insects, each trachea is a separate existing trunk. It proceeds precisely from the valve through which the spiracle passes. Branches, which are presented in the form of a spiral, come from the tracheal tube. Each such twig is formed from a very dense cuticle, which is always securely fixed in place. Due to this, the branches do not subside, do not tangles, therefore, gaps through which oxygen, carbon dioxide, and also water vapor can normally circulate in the body of an insect , without which the life of this class is unreal.
What is the difference between flying insects?
The respiratory system of insects that can fly looks a little different. In this case, their organisms are equipped with so-called air bags. They are formed due to the fact that the tracheal tubes expand. Moreover, these extensions are much larger than the pristine width of the respiratory organ. Another characteristic feature of such bags is that they do not have spiral seals, therefore they behave much more mobile inside the body of an insect. The expansion and contraction of air sacs in flying insects occur passively. During inhalation, the body increases; during exhalation, it accordingly decreases. In this process, only the muscles that control everything are involved. It is also important to note that the respiratory system of insects that are flying is designed so that they can capture a greater amount of oxygen for a longer period.
Insects that have gills
Arthropod inhabitants of water bodies, like fish, have gills and gill holes. At the same time, the respiratory process is still carried out thanks to the trachea, but this system in the body is closed. Thus, oxygen from the water does not enter the body through the spiracles, but through the gill slits, after which it enters the tubes and spirals. If the insect is arranged in such a way that with the process of growing up, it gets out of the aquatic environment, begins to dwell on the ground or in the air, then the gills become a rudiment that disappears. The tracheal system begins to develop more actively, the tubes and spirals grow stronger, and the breathing process no longer has anything to do with the gills.
Conclusion
We briefly examined which respiratory system in insects, how it is characteristic, and what types of it can be found in nature. If you dig deeper, you can find out that the respiratory systems of arthropods of various categories are very different from each other, and most often their features depend on the habitat of certain species.