Of course, fish and other aquatic inhabitants have a heart that has similar characteristics to a human one, performing its main function of supplying the body with blood. Unlike the human circulatory system, fish only have one circle and that one is closed. In simple, cartilage-free fish, blood flow occurs in straight lines, and in higher cartilage, in the form of the English letter S. This difference is due to the more complex structure of the organs of the circulatory system and different blood composition. At the beginning of the article, we will consider the heart of simple fish, and after that we will move on to the amazing cartilaginous inhabitants of the water world.
Important organ
The heart is the main and main organ of any circulatory system. Fish, like humans and other animals, have a heart. This may seem strange, because fish are cold-blooded animals, unlike us. This organ is a muscle sac, which is constantly contracting, thereby pumping blood to the whole body.
What kind of heart does a fish have and how does blood flow, you can find out by reading the information in this article.
Body size
The size of the heart depends on the total body weight, so the larger the fish, the greater its "motor". Our heart is compared with the size of a fist, fish have no such possibility. But as you know from biology lessons, a small fish has a heart the size of only a few centimeters. But in large representatives of the underwater world, an organ can reach even twenty to thirty centimeters. These fish include catfish, pike, carp, sturgeon and others.
Where is the heart located?
If someone cares about how many hearts the fish have, we will immediately answer - one thing. It is surprising that this question may arise at all, but as practice shows, it can. When cleaning fish, very often the housewives do not even suspect that they can easily find the heart. Like a person, the heart of the fish is in the front of the body. More specifically, right under the gills. On both sides, the heart is protected by ribs, like ours. In the figure that you see below, the main organ of the fish is indicated by number one.
Structure
Considering the peculiarities of fish breathing and the presence of gills in them, the heart is arranged differently than in terrestrial animals. Visually, the heart of the fish is similar in shape to ours. A small red pouch, with a small pale pink pouch underneath, is this organ.
The heart of cold-blooded aquatic inhabitants has only two chambers. Namely, the ventricle and atrium. They are located in close proximity, or rather, one above the other. The ventricle is under the atrium and has a lighter shade. Fish have a heart made up of muscle tissue, which is due to the fact that it acts as a pump and contracts continuously.
Blood circulation
The heart of the fish connects to the gills with the help of arteries, which are located on both sides of the main abdominal artery. It is also called the abdominal aorta, in addition, from the whole body to the atrium, thin veins lead through which blood flows.
The blood of the fish is saturated with carbon dioxide, which must be processed as follows. Passing through the veins, blood enters the heart of the fish, where it is pumped through the arteries through the arteries into the gills. The gills, in turn, are equipped with many thin capillaries. These capillaries pass through all the gills and help to quickly transport the pumped blood. After that, it is in the gills that carbon dioxide is mixed and changed to oxygen. That is why it is important that the water where the fish live is saturated with oxygen.
Oxygen blood continues its journey through the body of the fish and goes to the main aorta, which is located above the ridge. Many capillaries branch from this artery. Blood circulation begins in them, more precisely, an exchange, because, as we recall, oxygen-rich blood returned from the gills.
The result is a substitution of blood in the body of the fish. Blood from arteries, which usually looks rich red, changes to blood from veins, which is much darker.
Direction of blood circulation
The chambers of the heart of the fish are the atria and ventricle, which are equipped with special valves. It is due to these valves that the blood moves in only one direction, excluding reverse casting. This is very important for a living organism.
Veins direct blood to the atrium, and from there it flows to the second chamber of the heart of the fish, and then to the special organs, the gills. The last movement occurs with the help of the main abdominal aorta. Thus, you can see that the heart of the fish makes many endless contractions.
Cartilaginous fish heart
This special class of fish is characterized by the presence of a skull, spine and flat gills. The most famous representative of this class can be called sharks and stingrays.
As with their cartilaginous congeners, the heart of cartilaginous fish has two chambers and one circle of blood circulation. The process of exchanging carbon dioxide for oxygen takes place in the same way as described above, with only a few features. These include the presence of a splatter, which helps water get into the gills. And all because the gills of these fish are located in the abdominal region.
Another distinctive feature is the presence of such an organ as the spleen. She, in turn, is the ultimate stoppage of blood. This is necessary so that at the time of special activity there is a rapid supply of the latter to the desired organ.
The blood of cartilaginous fish is more saturated with oxygen, due to the large number of red blood cells. And all because of the increased activity of the kidneys, where their development occurs.