Fish, like mammals and the rest of the animals that populate the earth, need oxygen to be able to survive and carry out all their activities. To swim, reproduce, eat, etc., they need great contributions of energy and oxygen that they cannot get through the air.
Just as we cannot breathe in water without drowning, fish, if they stay out of the water long enough, also die. Then, How do fish breathe?Where do they get oxygen? At UnHowTo.com we are going to solve it for you, explaining how fish and other aquatic animals have developed a complex system that allows them to obtain the oxygen inputs necessary to live, even if they are underwater.
How fish breathe
Fish breathe through complex organs called gills, which in most species are located on both sides of the head, under a protective mobile membrane called the operculum.
Since oxygen dissolves 30 to 40 times worse in water than in air, fish and other aquatic animals have been forced to evolve so that they can live in water and get the oxygen they need.
In most fish this system is the gills, which through the so-called countercurrent exchange, manage to transfer the oxygen from the water to their blood, for this they swallow water through the mouth, forcing it out through the gills and there, they have a dense network of blood vessels and blood flow that circulates in the opposite direction to the water. In this way you can ensure that you will optimize this exchange to the maximum, in fact, the fish they stay with up to 85% of the oxygen that contains the water they filter.
The gills of the fish
How do they get oxygen out of the water? Although we have already explained the functioning of the gills a little, perhaps it is a bit complicated to understand the whole process.
In modern bony fish, scientifically called teleosts and which are the majority today, the mouth and its cavity communicate with openings on the side of the pharynx, which are called gill slits, from which the gills develop. These are protected by the covers, the solid structures located on each side of the head, the typical slits on the sides so characteristic of fish.
Curved structures called branchial arches pass between the gill slits, they are two rows of filaments that come together to form a V. From these filaments are born some folds or secondary sheets, between 10 and 40 each mm, formed by tissue and a large number of vessels blood.
In this way, when the fish opens its mouth, the oxygen-filled water enters through it, it passes through this entire structure and leaves through the operculum, but in between, it circulates in the opposite direction by the blades, which are trapping all the oxygen they can.
Other breathing methods in fish
By lungs
There are at least 400 species of teleosts that use the air to breathe, the vast majority freshwater fish, although almost all also retain their gills and use each system as they please.
Lung breathing is used when the oxygen level of the water drops, such as when the temperature rises, since the higher the temperature, the greater the need for oxygen.
However, there are also fish that only breathe through lungs, an example of this is the Lepidosiren, a South American species that has lungs with two lobes and very simple gills, so they need to breathe air if they do not want to die.
By the skin
Most fish, when they are born and have not yet developed the respiratory organs, take oxygen through the skin, although as the animal grows and develops the gills, respiration through the skin becomes more residual. However, skin respiration in some adult fish can be up to 20% of obtaining total oxygen.
If you want to read more articles similar to How fish breathe, we recommend that you enter our category of The Animal World.