Why the fish can't breath above water?

Answer 1

Simple... fish can breathe in water, as Oxygen is dissolved in the water already. Otherwise, its dangerous for the fish to breathe above water.

n order to live, fish must extract oxygen from the water and transfer it to their bloodstream. This is done by gills, lungs, specialized chambers, or skin, any of which must be richly supplied with blood vessels in order to act as a respiratory organ. Extracting oxygen from water is more difficult and requires a greater expenditure of energy than does extracting oxygen from air. Water is a thousand times more dense (heavier per unit volume) than air, and at 20 deg C (68 deg F) it has 50 times more viscosity (resistance to flow) than air and contains only 3% as much oxygen as an equal volume of air. Fishes, therefore, have necessarily evolved very efficient systems for extracting oxygen from water; some fishes are able to extract as much as 80% of the oxygen contained in the water passing over the gills, whereas humans can extract only about 25% of the oxygen from the air taken into the lungs.

Gills are made efficient in a number of ways. (1) A large surface area for gaseous exchange means that more oxygen can enter the bloodstream over a given period of time. A single gill of a bony fish consists of a curved gill arch bearing a V-shaped double row of gill filaments. Each filament has many minute folds in its surface, giving it a sort of fuzzy appearance and increasing the amount of surface area along a given length of filament. Consequently, the surface area of the gills is commonly 10 to 60 times more than that of the whole body surface. (2) A short diffusion, or travel, distance for the oxygen increases the rate of oxygen entry into the blood. The blood traveling in the folds of the filaments is very close to the oxygen-containing water, being separated from it by a very thin membrane usually 1 to 3 microns (4/100,000 to 1/10,000 in) thick, and possibly less. (3) By using countercurrent circulation in the gill, the blood in the filament folds travels forward, in the opposite direction to the water flow, so that a constant imbalance is maintained between the lower amount of oxygen in the blood and the higher amount in the water, ensuring passage of oxygen to the blood. If the blood were to flow in the same direction as the water, oxygenated blood at the rear of the gills would be traveling with deoxygenated water and not only could not extract oxygen from the water but would even lose oxygen to it. (4) Gills have little physiological dead space. The folds of the filament are close enough together so that most of the water passing between them is involved in the gas-exchange process. (5) Water flows continuously in only one direction over the gills, as contrasted with the interrupted, two-way flow of air in and out of lungs of mammals.

Answer 2

The fish can't breath above water because they have gills which can intake the only oxygen dissolved in the water but as they don't have nostrils they can't breath the oxygen in the air or outside the water.

Answer 3

A lot of fish can breathe above water. Eels, lungfish, mudskippers, snakeheads, carp and so forth are all perfectly capble of breathing above water provided they can remain moist.

The reason most fish struggle to breathe above water is because they have no skeletal support for their gills, which are thir primary organs fo obtaining oxygen.

Humans have ribs to support our lungs so we don't need to rely on water to suport them. Fish have no skeleton in thir gills, so as soon as they leave the water the gills collapse and cease functioning. No gills, no ability to breathe.

Those fish that can breathe abpve water do so through their skins or mouths, which are supported by bones and so don't collapse.

Answer 4

Why you cannot breath without OXYGEN? Like that Fish cannot breath above water?

Answer 5

They can while their gills remain wet. Gills are designed to remove oxygen from water and to excrete CO2 into the water in its soluable form. If there isn't a constant supply of clean water to the gills the CO2 can't be eliminated from the fishes body. The fish dies due to the build up of CO2 in its blood which causes acidosis.

Answer 6

Fish breathe with their gills. the structure of the gills is such that it stays properly lubricated & funstional only in presence of a liquid. In air the layers of blood vessels in the gills adhere to each other, thus losing their funtionality. So fish need an aquatic environment.

Answer 7

because of the method by which they extract the oxygen from the water. lol that sounded scientific right? They have gills, and the way they breathe is by filtering through the gills....if they were above the water there would be oxygen BUT they would have no way of getting it!!

Answer 8

gills are made of little finger like structures. they are like this to increase sufrace area to aid diffusion. these float around in water absorbing any oxygen which passes through them. when a fish is out of the water these "fingers" stick to each other and the surface area decreases alot. they don't get enough O2 and die.

Answer 9

Gills are designed to extract oxygen from water, not air.

Answer 10

The same reason you can't breathe below water.