Like vertebrates, invertebrate animals also need to breathe to stay alive. The breathing mechanism is very different from that of, for example, mammals or birds. The air does not enter through the mouth as is the case of the animal groups mentioned above, but through openings distributed throughout the body.
This type of respiration occurs especially in insects, an animal group of which there are more species on planet Earth and that is why on our site we want to tell you about tracheal respiration in animalsLikewise, we will show you what the tracheal respiratory system is like and some examples.
What is tracheal respiration in animals?
The tracheal respiration is a type of respiration that occurs in invertebrates, specifically in insects. If they are small animals or those that require little oxygen, it will enter the animal by diffusion through the skin, that is, along the gradient and without the need for an effort on the part of the animal.
In larger insects or at times of increased activity such as insect flight, the animal will need to ventilate so that the air enters its body through pores or spiracles in the skin that lead to structures called tracheoles and from there to the cells.
The pores can always be open or they can open some spiracles of the body and then others to come out, so they go air pumping their abdomenand the thorax, so that when you compress it the air will come out and when you expand it the air will enter through the spiracles. Even during flight they can use these muscles to pump air through the spiracles.
What is the tracheal respiratory system like in animals?
The respiratory system of these animals is highly developed It is made up of tubes that branch out throughout the animal's body and that they are filled with air. The end of the branch are the tracheoles, which dump oxygen into the body's cells.
Air reaches the tracheolar system through some spiracles, pores that open on the surface of the animal. From each spiracle a tube is generated that branches out becoming finer and finer until the tracheoles are built, where the gas exchange takes place
The end of the tracheoles is filled with fluid, and only when the animal is more active is the fluid displaced by air. In addition, these tubes are interconnected with each other, presenting longitudinal and transverse interconnections, which is known as anastomosis
Likewise, in some insects we can see air sacs, they are enlargements of these tubes that can occupy a large percentage of the animal and are used as bellows for air movement.
How does gas exchange occur in tracheal respiration?
Breathing with this type of system is discontinuous Animals have closed spiracles, so the air that is going to be in the tracheolar system is the one that undergoes gas exchange. The amount of oxygen locked up in the animal's body decreases and, conversely, the amount of carbon dioxide increases.
Then the spiracles start to open and close continuously causing a fluctuation where some carbon dioxide comes out. After this period, the spiracles open and all the carbon dioxide leaves, recovering the oxygen levels.
Tracheal respiration adaptations in aquatic insects
An insect that lives in water cannot open its spiracles under the water, otherwise its body would fill with water and it would die. There are different structures for gas exchange to occur:
Tracheal gills
They are gills that function similar to that of fish The water enters and only the oxygen that is in it passes into the system tracheolar that will distribute oxygen to all cells. These gills can be found on the inside of the body, on the back of the abdomen.
Functional spiracles
They will be some spiracles that can open or close. In the case of mosquito larvae, they lift the final part of their abdomen out of the water, open their spiracles, take a breath and re-enter the water.
Bubble Gill
There are two types:
- Compressible: An animal rises to the surface and grabs an air bubble. This bubble acts like a windpipe, you can take oxygen from the water through this bubble. The animal will gradually produce carbon dioxide, but this can easily pass into the water. IF the animal swims a lot or goes deep, the bubble will have a lot of pressure and will be smaller and smaller, so the animal will have to come to the surface to take a new bubble.
- Incompressible or plastron: this bubble will not change its size, therefore it can be indefinite. The mechanism is the same but the animal has millions of hydrophobic hairs in a very small region of its body that causes the bubble to remain enclosed in the structure and for this reason the bubble will never decrease.
Examples of tracheal breathing in animals
One of the animals that we can most easily see in nature is the water bunting (Gyrinus natator). This little water beetle breathes through a bubble gill.
The ephemeroptera or mayflies, also aquatic insects, during their larval and juvenile stages, breathe through tracheal gills When they reach the adult stage they leave the water, so these gills are lost and they pass to aerial tracheal breathing. The same happens with animals such as mosquitoes and dragonflies.
Grasshoppers, ants, bees or wasps, like many other terrestrial insects, have aerial tracheal respiration throughout their lives.
