osmoregulation in fishes?
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"Osmoregulation is the control of the levels of water and mineral salts in the blood"\n\nTherefore I say why not in fish?  They have blood and their blood also needs to have it levels regulated so it makes perfect sense. If you do not believe me here ya go :D\n\nWithout osmoregulation fish will die \n\nOsmoregulation is the control of the concentration of body fluids. If a fish is unable to regulate the effects of osmosis it will die. Clearly, osmoregulation is a vital function affecting all aspects of fish health.\n\nOsmosis, diffusion and fish health\n\nIf we look at the structure of the gill or gut under a powerful microscope we would see the tissue that lines these structures, the epithelium, is very thin, usually only one cell thick. Such areas are rich in blood vessels with very thin walls. The combined thickness of epithelium and blood vessels is less than the size of a full stop. The structure and thinness of these areas means that the minute particles whizzing around in the water (and blood) can pass through the epithelium and blood vessels with relative ease; in fact in many cases it is as if there wasn't any barrier at all!
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www.aquaticecosystems.com
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this is because gills of fish need a water flow through it so that the exchange of gasoues can occur
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Sensory and nervous system\nFishes have well-developed nervous systems that organize around a central brain, that is divided into different parts. The most anterior, or front, end of the brain are the olfactory bulbs, which are involved in the fish's sense of smell. Unlike most vertebrates, the cerebrum of the fish primarily processes the sense of smell rather than being responsible for all voluntary actions. The optic lobes process information from the eyes. The cerebellum coordinates body movements while the medulla oblongata controls the functions of internal organs. Most fishes possess highly developed sense organs. Nearly all daylight fish have well-developed eyes that have color vision that is at least good as a human's. Many fish also have specialized cells known as chemoreceptors that are responsible for extraordinary senses of taste and smell. Although they have ears in their heads, many fish may not hear sounds very well. However, most fishes have sensitive receptors that form the lateral line system. The lateral line system allows for many fish to detect gentle currents and vibrations, as well as to sense the motion of other nearby fish and prey. Some fishes, such as catfish and sharks, have organs that detect low levels electric current. Other fishes, like the electric eel, can produce their own electricity.
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There is no single mechanical form or chemical reaction to properly describe the process that fish gills use to remove oxygen from the water and get it into their blood system.\n\nThe site below is the single best resource to cover this topic:
80015
Yes; they need to, in order to maintain their internal ion/water balance (osmoregulation). Marine fish have to drink constantly to avoid dehydration; they have special cells in their gills to excrete the excess chloride.\nFreshwater fish face the opposite problem: their bodies tend to let water in and their internal ionic concentrations tend to become diluted. Therefore they drink water, retain the ions and afterwards excrete large volumes of very diluted urine. And they also have special cells in their gills for osmoregulation.
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ANY KIND OF ANIMAL WITH GILLS, SHARKS, FISH, ETC. I GUESS..
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salt helps maintain water in the body
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I suppose if you took a fresh water fish and put him in the ocean, he wouldn't be able to deal with the salinity and would dehydrate - essentially die of thirst!!
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Gall bladder of fish has nothing to do with the depth maintenance.\n\nIt is the AIR BLADDER in the abdomen of fish does the trick.
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SULLUS --- a genus of fish
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A lot of vertebrate metamorphosis study outside of amphibians is aimed at fish. Fish to look up include lamprey and flatfish. Vertebrate metamorphosis tends to be attributed to thyroid hormones. Unfortunately a lot of articles are in journals rather than online. The online stuff tends to be summaries/abstracts.\n\nAn introduction to the whole idea. It starts with invertebrates, but shows how the systems evolve up to vertebrates:\nhttp://www.thyroidmanager.org/Chapter1/index.html\n\nSpecific articles on the subject, mainly focusing on fish:\nhttp://www.sgnis.org/publicat/papers/az37_441.pdf\nhttp://findarticles.com/p/articles/mi_qa3746/is_199804/ai_n8798333\nhttp://www.ciwemb.edu/labs/schreiber/index.php\nhttp://www.findarticles.com/p/articles/mi_qa3746/is_199712/ai_n8778286\n\nA scientific journal article that might be useful if you can find it:\nWald, George (1958) The significance of vertebrate metamorphosis. Science 128:1481.\n\nYou may find more of interest in the references sections of the links provided.
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Biological Importance of Osmosis\n\nOsmosis and dialysis are of prime importance in living organisms, where they influence the distribution of nutrients and the release of metabolic waste products. Living cells of both plants and animals are enclosed by a semipermeable membrane called the cell membrane, which regulates the flow of liquids and of dissolved solids and gases into and out of the cell. The membrane forms a selective barrier between the cell and its environment; not all substances can pass through the membrane with equal facility. Without this selectivity, the substances necessary to the life of the cell would diffuse uniformly into the cell's surroundings, and toxic materials from the surroundings would enter the cell.\n\nIf blood cells (or other cells) are placed in contact with an isotonic solution, they will neither shrink nor swell. If the solution is hypertonic, the cells will lose water and shrink (plasmolyze). If the solution is hypotonic (or if pure solvent is used) the cells will swell; the osmotic pressure that is developed may even be great enough to rupture the cell membrane. Saltwater from the ocean is hypertonic to the cells of the human body; the drinking of ocean water dehydrates body tissues instead of quenching thirst.\n\nIn plants osmosis is at least partially responsible for the absorption of soil water by root hairs and for the elevation of the liquid to the leaves of the plant. However, plants wilt when watered with saltwater or treated with too much fertilizer, since the soil around their roots then becomes hypertonic.
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go to this site\n\nmembers.cox.net/tmccabe_2/SEASAND/ CapillaryCirculationinGoldfish.doc
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That depends entirely on the fish species and its age and lifestage.\n\nAs others have pointed out many fish like trout or eels will move from fresh water to salt as a normal part of their life cycle. Many other fish trevel between fresh and salt water at will.\n\nHowever if you take a purely freshwater fish, one that has evolved to live exclusively in fresh water, and you drop it into salt water it will  shrivel up and die.\n\nFish don't have waterproof skins. When you place a freshwater fish in salt water osmosis will draw water out of its body far faster than it can be replaced. The fish will become dehydrated and basically die of thirst.
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Fishes, as all other vertebrates, have closed circulatory systems; they have a single blood circuit in which the heart pumps the blood toward the gills where it picks up oxygen, and is then distributed to the body. However, our (human) anatomy is very derived with respect to aquatic pisciform vertebrates. In fishes the circulatory system is very symmetrical and more metameric. The best place to look is the gill area, where the major vessels occur. The heart, which looks like an elongated bulb, is situated ventrally right behind the gill basket. The ventral aorta is the major vessel extending forward below the gills, and emits branches to each functional gill. Once they go through the gill filaments, these vessels reunite dorsally and form the dorsal aorta (paired, then joined). Other vessels are difficult to observe as they usually collapse in dead materials, but if you have fresh large specimens you could try injecting a colored rubber solution (VERY carefully) inside the largest vessel you can find and if the walls are not broken, you will get an internal cast of part of the system. \nAlso look for the dorsal longitudinal vessels that are really close to the vertebrae, passing through the haemal arches.
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That depends on if you are a fish or a mammal. But mostly, you have to deal with the salt, either by excreting excess, tolerating high amounts and secreting or by maintaining the same concentration of salt inside your body as outside. Moving through the water also presents problems, such as streamlining and propulsion.\nIn marine mammals, their kidneys and urine are adapted to secrete high amounts of salts without loosing excess water, their body shape is made to move through the water easily and there is a seperation of the mouth and nasal cavity so they can eat underwater.