Insects are among the smallest animals on planet Earth. There are all kinds of them, flying, terrestrial and aquatic, each one with particular characteristics that allow the species to live in specific ecosystems.
In many ways, insects are different from most of the animals we know, because their morphology is different. One of these peculiarities is the way in which they obtain oxygen to survive. If you want to know where insects breathe and how insects breathe, don't miss the next article on our site. Keep reading!
The respiration of insects
The respiration process of insects occurs differently from that of other better-known animals, such as mammals. Mammals, for example, are characterized by obtaining oxygen through the nose, from where it passes to the lungs to be transformed into carbon dioxide that is expelled in the following exhalation; this is the basic explanation of the procedure. In insects, however, this mechanism is carried out differently. So how do insects breathe?
Insects take in outside oxygen through body tissues called spiracles, which are found in its exoskeleton, at the level of the abdomen, in the form of holes or openings in the body. When it is stored in the spiracles, the oxygen is transported to the tracheas of insects , tubes of smaller diameter that are distributed throughout the body and are responsible for carrying that oxygen to the tracheoles, sacs that measure less than 0.2 micrometers. These sacs act like the lungs of insects, only they are located in different parts of their anatomy. The tracheoles are distinguished as moist membranes that allow the exchange between gases that come from the outside and those that are inside.
Once this is done, the insect cells receive the oxygen they need and expel the corresponding carbon dioxide through the same spiracles. This movement of gases is carried out in the respiratory system of the insects, the circulatory system or other tissues are not involved. That is, how does an insect incorporate oxygen from the air and how does it reach its tissues? Through cellular respiration, exactly the same as humans and all living beings with cells. However, cellular respiration is the final part of the entire process, which involves gas exchange, therefore, if what we want to know is what type of respiration insects have, as we have been able to verify, follow a tracheal breathing system
This respiratory apparatus works the same for all terrestrial insects, with the exception that the smaller ones do not have to make an effort to maintain the functioning of the spiracles. The specimens of more than 3 centimeters, however, perform a greater muscular work to carry out respiration due to their higher metabolic rate; this is the case of Coleoptera, better known as beetles (such as the death watch beetle, also called Xestobium rufovillosum.
How do aquatic insects breathe?
Only 6% of insects are aquatic. Of the rest, some of them live during the first stages of their development in aquatic environments. How do you incorporate oxygen in these cases? How do aquatic insects breathe?
Adaptations of aquatic insects
Depending on the species, there are different mechanisms for insects to obtain oxygen. As with land insects, aquatic insects have a tracheal system, but they use it differently thanks to various adaptations. These adaptations are:
- Hydrophobic tracheae: prevent water from entering the insect's body, even when the spiracles are unfolded to carry out the respiration process. This is the method used by mosquito larvae.
- Hydrophobic siphons: these are “tubes” capable of breaking the tension of the water's surface. Diptera larvae belonging to the genus Eristalis use this adaptation, such as the bee fly (Eristalis tenax) and the orchard fly (Eristalis horticola).
- Hydrophobic hairs: with the intention of distancing visits to the surface, some species have developed bristles or villi capable of holding bubbles of air they use to extract oxygen. This adaptation is used by insects of the Notonecta genus, such as the back swimmer (Notonecta glauca).
- Plastron: plastrons are non-comprehensible bubbles thanks to which the insect is not obliged to go to the surface to breathe. The plastrons are formed thanks to the presence of hydrophobic hairs in the cuticle of the insect's body, which maintain a constant exchange of air without destroying the bubble. Insects of the genus Aphelocheirus (hemiptera such as Aphelocheirus aestivalis) and Elmis (coleoptera such as the beetle Elmis aenea) have plastrons.
- Tracheal gills: In the place where the tracheoles should be, some insects develop thin foliar extensions that can be seen on the outside of the body, are the tracheal gills. This system is used by the larvae of the Zygoptera suborder, such as the blue damselfly (Calopteryx virgo) and Trichoptera, such as the Stephens chimarra (Philopotamidae Stephens).
With these adaptations, aquatic insects have developed 3 types of respiration.
Types of respiration of aquatic insects
Tracheae, siphons and hydrophobic hairs, plastrons and tracheal gills are adaptations developed by aquatic insects to obtain oxygen in the following ways:
Obtaining oxygen from the air: to obtain oxygen directly from the air, the insect uses siphons, tracheae and hydrophobic hairs. There are three options:
- Break the tension on the surface of the water and use the hydrophobic tracheae to obtain oxygen. When this is exhausted, the insect must return to the surface.
- Break the surface tension and use the siphons to get oxygen. In this case, the insect must remain with the siphon extended to breathe.
- Break the surface tension and use the hydrophobic hairs to create an air bubble. Once the bubble is exhausted, the insect must return to the surface to repeat the process.
Obtaining oxygen through water: This is the case of skin respiration and the use of gills and plastrons. To find out how insects breathe using these methods, we explain them below:
- Skin respiration: some species that develop in aquatic spaces present the formation of a cuticle or external film through which they absorb oxygen gases found in water. In this type of respiration, oxygen is obtained directly from the water. Thanks to this method, no liquid enters the tracheal system because the insect is able to keep its spiracles closed until the oxygen runs out. This respiration is used by the larvae of the genera Simulium and Chironomus, Diptera such as the Blandford fly (Simulium posticatum).
- Tracheal breathing: this method consists of obtaining oxygen from the aquatic environment itself, without having to go near the surface. In these cases, the gills are found covering the trachea network of the insects, so from them the oxygen is distributed in the way we have already described.
- Plastrons:are formed thanks to the presence of hydrophobic hairs on the cuticle of the insect's body, which maintain a constant exchange of air without the bubble being destroyed.
Getting Oxygen Through Plants: Aquatic insects can also get oxygen directly from submerged plants. To do this, they press on the spiracles until they reach the aerenchyma of plants, an area of tissue with intercellular cells where they store oxygen (you can see it when cutting the stem of an aquatic plant and observing small hollow divisions inside). The insects that obtain oxygen in this way are the larvae of the genera Donacia (coleoptera such as Donacia jacobsoni and Donacia hirtihumeralis) and Chrysogaster (diptera such as Chrysogaster basalis and Chrysogaster cemiteriorum).
Thus, we see that the respiration of insects is much more complex and varied, so insects breathe in one way or another depending on the environment in which they live.
How do flies breathe?
Flies, those animals that are so common in homes, use the same tracheal breathing system as other insects terrestrial. The spiracle through which the oxygen particles enter is located in the abdomen. From there, they are transported by the tubes of the trachea to the tracheoles, the final destination of this oxygen.
The tracheoles contain tracheal fluid, responsible for dissolving oxygen molecules to take them to the fly's body. This process takes only a few seconds and occurs at all times, even while the fly is in flight. However, during flight, insects need to consume more oxygen and, therefore, the flow received must be increased. Although the spiracles distend to allow more air to pass through, this is not sufficient for the levels needed during flight. Due to this, the fly expands the thorax and the tracheal system, which multiplies the capacity of the tracheoles. Thanks to this system, the fly is capable of processing 350 milliliters of air per hour, instead of the 50 milliliters it processes at rest.
Now that you know how insects breathe, if you want to know more curiosities about them, don't miss this other article: "The largest insects in the world".
