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Do fish have lungs? How are fish able to breathe under fresh and salty waters around the world? Ichthyology is the science that is responsible for clarifying these and all those questions related to the amazing world of fish. Both the description of the anatomy, such as the respiration system of fish, and its ecology, are fascinating to learn more about the different habits and characteristics of different groups of fish.
Continue reading this interesting Green Ecologist article to discover how fish breathes, what the fish respiration system consists of, as well as the vital importance of the gills and other respiratory structures for the survival of these animals.
Where do fish breathe
Like the rest of the group of animals, fish need oxygen in their tissues to survive, thus meeting their fundamental energy needs to stay alive.
Fish obtain oxygen from the external environment thanks to vascularized gills, lungs, and even through the skin (in fish without scales), or by temporary respiratory structures (such as the yolk sac tissue of fish embryos). On the other hand, the blood of the fish's circulatory system also plays an important role in gas exchange, allowing the transport of carbon dioxide resulting from cellular oxidative processes to the gills and other respiratory structures for its correct elimination from the body.
In the following sections of the article we will see in detail the role played by both the gills and the lungs in the respiratory system of fish, as well as the characteristics of the complex breathing process.
What are the gills of fish like?
There are different structural types of gills in fish, depending on the group to which they belong, being able to be placed in the fish classification as: agnathans (fish without jaws: lampreys and hagfish), chondrichthyans (cartilaginous fish: sharks and rays) or osteichthians (bony fish: such as salmon and tuna).
They all share the presence of gill openings like external respiratory organs, generally constituted by a single opening on each side of the head, in front of the pectoral fin of the fish. These gills are made up of very fine epidermal filaments, adapting the structure of numerous folds rich in blood vessels.
The importance of the gills within the correct functioning of the respiratory process is vital to the survival of all fish. In the section dedicated to the explanation of the respiratory system of fish we will see in more detail how the gills work.
Did you know that fish are not the only ones with gills? In this other post from Green Ecologist we talk about 40 animals that breathe through gills.
What are the lungs like in fish?
Fish have developed different mechanisms throughout their evolution that allow them to get oxygen from the air when the amounts of oxygen in the aquatic environment are scarce or not sufficient to cover its vital energy needs. The lungs (and sometimes the gas bladder) are the main internal structures adapted to such air respiration, present in many tropical freshwater and some saltwater fish, during their temporary air respiration habit.
A) Yes, lungfish lungs They have the same respiratory function as that of the lungs of the other groups of vertebrate animals that take oxygen from the air. In this way, the lungs present internal septa and roughness that divide the air spaces into smaller compartments, ending in alveolar sachets covered by numerous blood vessels.
The smooth muscle present in the lungs of the fish that breathe out of water makes it possible for the respiratory mechanism to take care of providing and distributing air within the lung. In addition, the fish receive blood supply in their lungs from their last efferent branchial artery, subsequently returning the already oxygenated blood from the lungs to the heart.
How fish breathe - the respiratory system
The basic process that takes place in the fish respiratory system It begins with the use of oxygen from the water through the lamellar filaments of the gills. This uptake of oxygen is favored in turn by the direction of the body's own blood flow and by the circulation of water from the environment in which the fish lives. In this way, the countercurrent of blood and breathable water maintain a smooth diffusion gradient in the gills for oxygen to penetrate and carbon dioxide to release into the fish.
As inspiration begins, the protective covers of the gills close tightly and the fish opens its mouth, entering it the water with dissolved oxygen in her. Thanks to the contraction of different muscles, the water begins to flow through the gill lamellae, the oral cavity now functioning as a pumping system, thus preventing water from flowing out of the mouth.
Subsequently, both the gill cover and the gill fins open and the water is expelled from the body, also preventing the return of water through the action of an oral valve.
If you want to read more articles similar to How fish breathe, we recommend that you enter our category of Animal Curiosities.
Bibliography- Hickman, C. P., Ober, W. C. & Garrison, C. W. (2006) Comprehensive Principles of Zoology, 13th edition. McGraw-Hill-Interamericana (Madrid), pp: 765-789.
- Granado, C. (2002) Fish ecology. SSecretariat of Publications (Science Series), University of Seville, Volume 45.
- Teisaire, E., Nieto, O., Roldán, I., Kreisel, Z., López, M. & García, A. (2013) Comparative Anatomy of Vertebrates. Activities for the study of the respiratory organs. REDUCA Magazine (Biology), Zoology Series, Volume 6 (1), pp: 71-77.
- Lagler, K., Bardach, J., Miller, R. & Passino, D. (1984) Ichthyology. AGT EDITOR, S.A., pp: 215-244.
