Where do fish breathe is a frequently asked question by people of all ages; It seems that the respiratory system of these living beings has become a topic of conversation. And the truth is that his way of breathing represents a rarity for human beings; but to delve into this fascinating marine world, we will tell you a little about these aquatic animals.
It could be said that fish exist in 98% of freshwater or saltwater reservoirs. These were the first beings that populated our planet, more than 500 million years ago; which means that they are extremely long-lived beings; and yes, which also means that the rest of all the animals we know have a marine ancestor. There are fish of many shapes and sizes, with such varied physical characteristics that you could not imagine it. The largest existing fish is the so-called whale shark, which measures about 18 meters and can weigh 20 tons.
Like all living things, fish require oxygen to live; that is why there must be oxygen in the water, which the fish take in using their gills; which constitute the respiratory system of fish. The gills are a kind of plates that contain blood vessels; these are generally located at the beginning of the digestive system. The respiratory process of fish is very interesting compared to that of human beings.
In fact, there are fish that can also breathe outside their natural habitat and not only in the water. These are fish such as catfish, which have evolved by adapting to the environment in which they develop. Catfish usually get out of the water and even travel long distances for a couple of days using their fins. These fish breathe through the intestine but also reserve enough oxygen to stay out of the water for a long time.
There are also fish with lungs, that’s right! Like those of a human; it is a class of fish called dipnoans or lungfish that develop a functional lung organ; these lungs are located on the ventral wall, the end of the pharynx. They use their lungs to breathe when the environment they live in dries up.
Instructions
Fish can breathe shallow, but you already knew that; what you don’t know is the mechanism by which these animals can extract oxygen from the water. Due to its density and composition, the oxygen in water is much lower; but this is not a problem for the fish; because their respiratory system is composed in such a way that they can obtain the oxygen they need.
Fish breathe through gills, which are membranes that absorb oxygen from the water. The gills are located on the sides of the fish, in the middle of the pharynx and the mouth. While they are swimming, the water enters the fish’s mouth, which is constantly opening and closing; when the water enters, the blood vessels found in the gills absorb the oxygen, said oxygen is transported throughout the bloodstream, in a process that is repeated instantly.
Almost all fish have an operculum, which is an area that covers the gills to protect them. As soon as the fish’s mouth opens, the operculum closes to conserve water; when the fish closes its mouth, the operculum opens allowing the water to pass through the gills. The gills contain filaments called lamellae, which carry oxygen to the bloodstream. In this same process, the carbon dioxide contained in the fish’s blood is released into the water.
There are aquatic species that can absorb a little oxygen through their skin, but in their larval stage. But apart from this, there are other breathing systems of aquatic beings such as that of dolphins and whales; these processes are very different from the one we have just explained.
Contrary to what may be believed, whales and dolphins are mammals and not fish that are right! They take in oxygen in a process similar to that of human beings. Dolphins do this using the hole in the back of their head, through which they expel water. Said hole is called a spiracle, when it comes out of the water, it sucks in oxygen from the environment to the lungs; a dolphin can spend about an hour swimming underwater before taking a breath again.
Whales also breathe through blowholes like dolphins . Some types of whales, such as baleen whales, have two blowholes, which resemble the holes in a human nose.
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There are countless fish, there are so many species, shapes, sizes and types that classifying them is an arduous task. However, to speak of fish in general is to refer to underwater-breathing cold-blooded vertebrate marine animals; they are considered blood not because they have a cold blood temperature; but because their blood adapts to various types of marine environments; that is, if the water is hot like in streams, the fish will be warm-blooded; but river fish for example have a low blood temperature.
Fish do not have legs like other animals but fins and breathe through gills. Although scales are a characteristic quality of fish, not all have them.
Most fish are oviparous and their fertilization process takes place externally; which means that the sexual act of the fish is not through physical contact; fertilization occurs when the female releases her ovules so that the male fertilizes them with her sperm; This process gives rise to the eggs from which the larvae that will become fish will be born. There are exceptional cases in which fertilization takes place internally, such as the Mexican four-eyed fish.
Most fish are carnivorous animals, although certain herbivorous species do exist. To devour their food, the fish have sharp teeth; but there are cases in which instead of teeth, they have a kind of strainer or more sensitive fibers; these fibers are used to engulf small organisms, as in the case of the whale shark that does not have teeth.
The defense system of fish is very diverse and depends on the species; the most common is to swim away very fast, but others hide through mimesis; they camouflage themselves in the environment that surrounds them like the surgeon fish, which blends in with the color of the ocean.
The habitat of the fish is the marine environment as we already mentioned, but these can have very varied characteristics among themselves. According to the type of environment, there will be a series of marine species that develop in it. Here are the places where fish can live:
- Rivers and streams.
- Hot springs and caves.
- Lakes and ponds.
- The ocean.
- Tropical regions such as coral reefs.
- Polar Regions as glaciers.
- Temperate regions, where the largest number of fish that can be consumed by humans come from.
Tips
Oxygen is the essential element for the life of every being; adequate oxygenation of the water is of vital importance for the fish, plants and microorganisms in an aquarium. That is why you must make sure every day that your aquariums have the necessary amount of oxygen. Naturally, oxygen reaches the water through two processes:
- Through the absorption of oxygen in the air, through gaseous exchange between the water and the surface.
- Or through the photosynthesis of aquatic plants during periods of light.
- Oxygen reaches the water more extensively by the first process; which means that depending on the size of the aquarium, there will be greater absorption of oxygen. The amount of fish, plants and microorganisms that inhabit the aquarium will determine the amount of oxygen that will be required. In such a way that if the aquarium is large enough for its occupants, extra oxygen will not be necessary.
- But if the opposite of the previous case occurs, that the oxygen that is obtained through the exchange is insufficient; it will be necessary to resort to artificial means to provide the necessary oxygen to the inhabitants of the aquarium. To provide more oxygen to the water, or as necessary, you can use a water aerator.
- These systems cause much higher oxygen uptake through the use of bubbles; which set the water in motion, generating currents that spread oxygen throughout the aquarium. Here ‘s how aerators work in aquariums:
- If the water is in motion, it will absorb more oxygen. So an aquarium with certain currents is the most ideal for such absorption.
- Aerators release air bubbles that cause currents and ripples on the aquarium surface; these undulations increase the contact space between water and air, which means greater oxygen exchange.
- Generally, in aquariums without aerators, a very thin film of dust settles, preventing the passage of oxygen; with the aerator generating movements in the water, this film breaks and allows oxygen to enter.
- In the same way, carbon dioxide remains on the surface of the aquarium, which also prevents the passage of air; the aerator contributes with its water movements to dislodge it.
