Of course, fish and other aquatic inhabitants have a heart that has similar features to a human, performing its main function of supplying the body with blood. Unlike the human circulatory system, fish have only one circle and that one is closed. In simple cartilaginous fish, the blood flow occurs in straight lines, and in higher cartilaginous fish, in the shape of the English letter S. This difference is due to the more complex structure of the organs of the circulatory system and the different composition of the blood. 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 aquatic 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 bag that is constantly contracting, thereby pumping blood throughout the body.
What kind of heart do fish have and how does blood flow, you can find out by reading the information in this article.
Organ size
The size of the heart depends on the total body weight, so the larger the fish, the larger its "motor". Our heart is compared to the sizefist, fish do not have such an opportunity. But as you know from biology lessons, a small fish has a heart only a few centimeters in size. But for large representatives of the underwater world, the organ can even reach twenty to thirty centimeters. Such fish include catfish, pike, carp, sturgeon and others.
Where is the heart?
If someone cares about the question of how many hearts a fish has, we will immediately answer - one. It is surprising that this question can arise at all, but as practice shows, it can. Very often, when cleaning fish, the hostesses do not even suspect that they can easily find the heart. Like humans, the heart of fish is located in the anterior part of the body. To be more precise, right under the gills. On both sides, the heart is protected by ribs, like ours. In the picture you see below, the main organ of the fish is number one.
Building
Given the peculiarities of fish breathing and the presence of gills, the heart is arranged differently than in land animals. Visually, the heart of fish is similar in shape to ours. The little red pouch, with a little pale pink pouch underneath, is the organ.
The heart of cold-blooded aquatic creatures has only two chambers. Namely, the ventricle and atrium. They are located in close proximity, or to be more precise, one above the other. The ventricle is located under the atrium and has a lighter shade. Fish have a heart made of muscle tissue, this is due to the fact that it acts as a pump and is constantly contracting.
Circulation scheme
The heart of fish is connected to the gills by arteries that are located on either side of the main abdominal artery. It is also called the abdominal aorta, in addition, thin veins lead from the whole body to the atrium, through which blood flows.
The blood of 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 to the gills with the help of the atrium. The gills, in turn, are supplied 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 exchanged for oxygen. That is why it is important that the water where the fish live is saturated with oxygen.
Oxygenated blood continues its journey through the body of the fish and is sent to the main aorta, which is located above the ridge. Many capillaries branch off from this artery. Blood circulation begins in them, more precisely, exchange, because, as we remember, blood saturated with oxygen returned from the gills.
The result is a replacement of blood in the body of the fish. Arterial blood, which normally looks deep red, changes to vein blood, which is much darker.
Circulation direction
The chambers of the heart of fish are the atrium and ventricle, which are equipped with special valves. It is due to these valves that the blood moves in only one direction, excluding reverse reflux. This is very important forliving organism.
The veins direct blood to the atrium, and from there it flows to the second chamber of the fish's heart, and then to 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.
Heart cartilaginous fish
This special class of fish is characterized by having a skull, backbone and flat gills. The most famous representative of this class can be called sharks and rays.
Like their cartilaginous relatives, the heart of cartilaginous fish has two chambers and one circulation. The process of exchanging carbon dioxide for oxygen occurs in the same way as described above, with only a few features. These include the presence of a spray, which helps water get into the gills. And all because the gills of these fish are located in the abdominal region.
Another distinctive feature can be considered the presence of such an organ as the spleen. She, in turn, is the final stop of the blood. This is necessary so that at the moment of special activity there is a quick supply of the latter to the desired organ.
The blood of cartilaginous fish is more oxygenated due to the large number of red blood cells. And all because of the increased activity of the kidneys, where they are produced.
