The fish drinks water. Do fish drink? Why can't fish live in any environment?

Do you think fish drink? I can already see your smile. After all, as soon as a fish opens its mouth, it is full of water.

And along with food, inevitably, whether the fish wants it or not, a certain amount of water enters the stomach. Is it enough? Do fish get thirsty? Scientists have long found an answer to these questions.

Modern fish have mastered all natural bodies of water, but each species can live only in the conditions familiar to it. Very few people can move from fresh water to salt water and back without harm to their own health. Eels can be considered virtuosos in this area. They spend half their life in salt water and the other half in fresh water. What prevents fish from freely moving from one water to another? The skin, integument of the mouth, gills and other parts of the body, as well as the membranes of individual cells of all organs and tissues of fish are permeable to water. It seeps through them freely, and these shells are impermeable to salts and most other substances.

Where will the water leak: into the reservoir or out of the reservoir? It does not depend at all on where there is more of it. The diffusion process is controlled by the osmotic pressure of solutions, which is created by the substances dissolved in them. The more there are, the higher the osmotic pressure and the stronger the solution absorbs water. In fresh water it is practically zero, but in the blood and tissue fluids of fish there are a lot of salts and protein substances, which create an osmotic pressure of 6–10 atmospheres. With this force, the body of freshwater fish sucks water, which intensively enters their body from the outside. If they did not have devices for quickly removing its excess from the body, the body would quickly swell and the animal would die. Thus, freshwater fish never need to drink water.

Another thing is their relatives - marine bony fish. There are much more salts in seawater than in fish tissues. The osmotic pressure of ocean water is 32 atmospheres, while in the body of marine bony fish it reaches only 10–15. Therefore, the insatiable ocean greedily sucks water from their bodies. At first glance, a paradoxical phenomenon arises: sea water can dry out fish swimming in it. No wonder they are always thirsty.

Not all sea fish drink water. The most ancient of them, sharks and rays, which apparently moved to the ocean earlier than bony fish, otherwise adapted to life in salt water. They have learned to retain a rather harmful substance in the blood - urea, which all other animals rush to get rid of as quickly as possible. To do this, they had to put the gills in a special shell, impenetrable to urea. The osmotic pressure of the blood of sharks and rays is much higher than that of sea water. Their bodies, just like freshwater fish, suck water from the ocean, so sharks and rays are only concerned with how to get rid of it.

The same principle was borrowed from sharks by the crabeater frog, which scientists recently discovered in Southeast Asia. Of all the amphibians, it is the only one that has adapted to life in salt water. True, these frogs still spawn in fresh water, but when the frogs grow up, they go to the sea, where they feed on crabs. Like sharks, frogs retain urea in their blood, but they do it voluntarily: before moving into sea water, they stock up on urea, and when they go into fresh water, they are freed from its excess. Therefore, no matter where they live, these frogs, like the rest of their relatives, do not need to drink water.

Having studied all aspects of the problem, scientists found out that fish do not drink the same way. It’s even better to say - they don’t drink, but get water into their body. After all

liquid is involved in all metabolic processes. Without it, life would be impossible. This is what they got.

Freshwater inhabitants

These beauties have so many salts in their bodies that they do not need to swallow water to ensure metabolism. It turns out that fish drink with their bodies and not with their mouths. The process can be schematically represented as follows. If two liquids that differ in the concentration of salts dissolved in them are placed side by side and the damper is opened, where will the diffusion vector be directed? That's right, towards a more saturated liquid. The higher the concentration of salts, the greater the “thirst” torments. Water begins to move towards a saturated solution, contains a small amount of additives, and its osmotic pressure is almost zero. But for fish it’s the opposite. There are a lot of salts in their body. It turns out that they are constantly sucking in the environment. And their main task

is not absorption, but excretion. This process is established, otherwise freshwater inhabitants may swell and burst, so great is the flow into the body. It turns out that fish drink in a very original way. They absorb liquid for their own needs, and also regulate its pressure inside themselves.

Sea inhabitants

For these inhabitants the process is reversed. There is a high concentration of salt in the sea. The osmotic pressure indicator is thirty-two atmospheres. drink continuously. They are simply forced to constantly replenish their reserves, because the environment constantly “dries” them, water seeps out through the entire body. The fact is quite comical. When sea fish drink water, they are alive and well. If they stop, they can “dry up” and die from loss of fluid. And this while constantly being in the water! But these are the laws of diffusion. inside fish bodies there are only ten to fifteen atmospheres. Outside - more than twice as high. So the poor fish have to drink continuously in order to survive and not dry out. Interestingly, they need fresh water to survive. They “filter” it, removing remaining salts through their gills. Crocodiles, for example, can do the same. They remove salts through

lacrimal glands. When the crocodile eats something sweet, he cries. These excess salts leave the body.

Sharks and rays

These inhabitants of the world's oceans were allocated to a special class. The reasons for this “prejudiced” attitude are that the mechanisms of their relationship with the environment are very different from other inhabitants of the deep sea. These fish do not drink as much as the others. They “learned” to deal with the problem of osmotic pressure differences differently. They retain urea in their circulatory system, although this is very harmful. These creatures even have a special membrane in their gills - protection from excess salts. Thus, rays and sharks maintain internal salt concentrations higher than in the surrounding area. Scientists believe that this is an indicator of the antiquity of these inhabitants of the seas. They, like freshwater ones, absorb liquid throughout their bodies.

Why can't fish live in any environment?

The difference in the mechanisms of interaction with liquids does not allow them to explore the entire space of the world's oceans. Those who thrive in fresh water will die in sea water. And vice versa. There are exceptions to this rule. So, everyone knows well that some fish live well in salt water and breed in rivers. That is, they are diadromous - they can live in any environment. Whether the fish drink water in this case depends on the state of the surrounding liquid. They sense with their bodies which direction the process is moving, and if necessary, they begin to consume water. Their internal organs quickly

adapt to the environment. For example, salmon, puzankas, sturgeon and some other fish are diadromous. While they splash in the sea, they drink just like all its inhabitants. When they go to spawn, their gills quickly adapt to their environment. Therefore, they do not die from moving into water with a different salt concentration. The reverse process occurs in the body of their fry when they descend into their natural habitat - the sea.

Scientists have found another inhabitant who can regulate in an original way. The crabeater frog, a recently discovered amphibian, leads a strange lifestyle. It lives in the sea and breeds in freshwater environments. How is this possible? For this purpose, nature has invented a special mechanism. In order not to die, she can adjust the level. When she dives into the sea, she accumulates it. When he gets ready to spawn, he gets rid of urea. And little frogs, when they grow up, also learn to use this mechanism for their journey between bodies of water. These are the wonders of nature!

It turns out that it is impossible to answer unequivocally the question of whether fish drink. Naturally, they, like any living organism, need moisture. Only they receive it in their own way, as provided by natural mechanisms.

Although sea ​​fish They drink a lot of water; their freshwater relatives drink almost nothing. The root of this difference lies in the need of fish to maintain a normal balance of salt and water in the body.

The water in the ocean is three times saltier than the own liquid environment of the fish living in the ocean. Through a natural process known as osmosis, water from a marine fish's body flows out through its skin and gills. To replace lost fluid, saltwater fish are forced to absorb large amounts of seawater.

The concentration of salt in the body of freshwater fish exceeds its content in the surrounding aquatic environment, therefore freshwater fish do not drink like sea fish, but constantly absorb water through the skin. They excrete excess fluid in the form of excessive urination.

1. The amount of water that marine fish absorb depends on the degree of salinity. The saltier the water, the more the fish drinks.

2. The gills of fish that live in salt water absorb some salt.

3. By osmosis, fish can pass large amounts of water through their gills.

4. Excess salt is excreted in the urine.

5. Water swallowed by saltwater fish is absorbed by the intestines.

Freshwater fish secrete salt and absorb water through their skin, so they don't need to drink water. The level of salt in the body of freshwater fish is replenished with food and ions (salt) deposited in the gills.

1. Driven by the force of osmosis, water enters the fish's body through the gills.

2. Some of the salt is lost by the gills as a result of osmosis.

3. Freshwater fish have excess water, which they excrete as very dilute urine.

If the fish are swapped

In their usual home, sea fish maintain a normal water-salt balance by drinking large amounts of water and excreting excess salt. In fresh water, saltwater fish absorb water, diluting the liquid environment of their body with it. Unable to retain salt or get rid of excess water, the fish dies.

Typically, freshwater fish regulate the salt levels in their body tissues by absorbing salt and excreting water. In salt water, fish lose water that they cannot replace; The salt content in her body rises to lethal levels.

Fickle natures

Several species of fish are diadromous, meaning that they can live in both salt and fresh water, adjusting their body fluids to suit environmental conditions. They drink water - or abstain from it - depending on the salt concentration in their habitat. In addition, their gills and kidneys are able to quickly switch from processing salt water to fresh water, and vice versa. Salmon, which live in the ocean and spawn in rivers, as well as sturgeon, panther and lamprey, which live in river mouths, are also among the easily adaptable fish. Some species of diadromous fish are shown in the illustration above.

Answered by Evgenia Prisekina, ecologist

Of course, fish drink water, but not all of them. This feature is inherent in marine fish, but not in freshwater. The reason is simple: it all depends on the balance of salt and water in the body.

The saltier the water, the more the fish drink. Marine inhabitants consume the surrounding liquid very willingly - mainly with the help of gills, although some of the liquid can be swallowed with food. The amount of water consumed depends on the degree of its salinity. Excess salt in the body is excreted in urine.

For freshwater fish, everything is different. The concentration of salt in their body is higher than in the environment. Therefore, they do not drink, but only absorb liquid through their skin. Freshwater fish replenish the salt level in the body with food and salt ions deposited in the gills. Excess water is also excreted in urine.

What happens if freshwater fish are swapped with saltwater fish? Most likely, they will die because they are not adapted for this environment. But every rule has its exception, and in this case it is diadromous fish. Some live in fresh water bodies and go to salt water bodies to reproduce, others do the opposite, and still others migrate from fresh water bodies to sea water bodies, regardless of the need to procreate. Diadromous fish include chum salmon, salmon, freshwater eel, etc. They can adapt to environmental conditions. In addition, their gills and kidneys are able to quickly switch from processing fresh water to salt water - and vice versa. Therefore, such fish can be found both in rivers and seas.

For some, the restructuring of water-salt metabolism to the marine type is irreversible. An example is Pacific salmon, which changes its system only once and also spawns only once in its life. And other fish rearrange themselves several times - Kamchatka salmon, char.

if (typeof(pr) == "undefined") ( var pr = Math.floor(Math.random() * 4294967295) + 1; )
if (typeof(document.referrer) != "undefined") (
if (typeof(afReferrer) == "undefined") (
afReferrer = encodeURIComponent(document.referrer);
}
) else (
afReferrer = "";
}
var addate = new Date();
document.write("’);
// —>

(function(w, d, n, s, t) (
w[n] = w[n] || ;
w[n].push(function() (
Ya.Context.AdvManager.render((
blockId: "R-163191-3",
renderTo: "yandex_ad_R-163191-3",
async: true
});
});
t = d.getElementsByTagName("script");
s = d.createElement("script");
s.type = "text/javascript";
s.src = "//an.yandex.ru/system/context.js";
s.async = true;
t.parentNode.insertBefore(s, t);
))(this, this.document, "yandexContextAsyncCallbacks");

Although saltwater fish drink a lot of water, their freshwater relatives drink almost nothing. The root of this difference lies in the need of fish to maintain a normal balance of salt and water in the body. The water in the ocean is three times saltier than the own liquid environment of the fish living in the ocean. Through a natural process known as osmosis, water from a marine fish's body flows out through its skin and gills. To replace lost fluid, saltwater fish are forced to absorb large amounts of seawater. The concentration of salt in the body of freshwater fish exceeds its content in the surrounding aquatic environment, therefore freshwater fish do not drink like sea fish, but constantly absorb water through the skin. They excrete excess fluid in the form of excessive urination.

1. The amount of water that marine fish absorb depends on the degree of salinity. The saltier the water, the more the fish drinks.

2. The gills of fish that live in salt water absorb some salt.

3. By osmosis, fish can pass large amounts of water through their gills.

4. Excess salt is excreted in the urine.

5. Water swallowed by saltwater fish is absorbed by the intestines.

Freshwater fish secrete salt and absorb water through their skin, so they don't need to drink water. The level of salt in the body of freshwater fish is replenished with food and ions (salt) deposited in the gills.

1. Driven by the force of osmosis, water enters the fish's body through the gills.

2. Some of the salt is lost by the gills as a result of osmosis.

3. Freshwater fish have excess water, which they excrete as very dilute urine.

If the fish are swapped

In their usual home, sea fish maintain a normal water-salt balance by drinking large amounts of water and excreting excess salt. In fresh water, saltwater fish absorb water, diluting the liquid environment of their body with it. Unable to retain salt or get rid of excess water, the fish dies.

Typically, freshwater fish regulate the salt levels in their body tissues by absorbing salt and excreting water. In salt water, fish lose water that they cannot replace; The salt content in her body rises to lethal levels.

Fickle natures

Several species of fish are diadromous, meaning that they can live in both salt and fresh water, adjusting their body fluids to suit environmental conditions. They drink water - or abstain from it - depending on the salt concentration in their habitat. In addition, their gills and kidneys are able to quickly switch from processing salt water to fresh water, and vice versa. Salmon, which live in the ocean and spawn in rivers, as well as sturgeon, panther and lamprey, which live in river mouths, are also among the easily adaptable fish. Some species of diadromous fish are shown in the illustration above.