How do Fish Drink?
23 December 2001, 12:41 PM
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Seems an obvious answer, but i'm not so sure. If I recall salt water can cause all kinds of cell problems(Osmotic pressure???) by causing water to be 'sucked' out of the cells and into the surrounding tissues. If I recall that's one of the reasons why sea water is bad to drink in quantity.
So how do Salt water fishes drink, so that the sea water does'nt harm them?
So how do Salt water fishes drink, so that the sea water does'nt harm them?
23 December 2001, 01:01 PM
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Neil, I don't know the scientific answer, but don't forget that "salt water" vs "fresh water" is arbitrary. In fact, one of the first things you do when you have parasites in your "normal" pond is throw in a lot of salt (up to 0.1 % salinity).
It helps to build up their slime coat and thus become better protected.
When you start reading up on these things, it becomes obvious that a car engine is a lot simpler than water chemistry
And with less heated debates even 
The choice of Link vs Unichip etc is a breeze in comparison to the use of salt, potassium permangate, limestone, barly straw, fresh water clams, activated charcoal, nitrifying bacteria, in line UV installations etc ... LOL
[Edited by EvilBevel - 12/23/2001 1:02:11 PM]
It helps to build up their slime coat and thus become better protected.
When you start reading up on these things, it becomes obvious that a car engine is a lot simpler than water chemistry
And with less heated debates even The choice of Link vs Unichip etc is a breeze in comparison to the use of salt, potassium permangate, limestone, barly straw, fresh water clams, activated charcoal, nitrifying bacteria, in line UV installations etc ... LOL
[Edited by EvilBevel - 12/23/2001 1:02:11 PM]
23 December 2001, 01:07 PM
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Osmotic regulation
Marine fish live in a medium of greater concentration than their body fluids; this means that they tend to gain salts by diffusion and lose water by osmosis. To offset the loss by osmosis, they drink sea water, most of which their kidneys are able to retain – the salt is excreted, often through special cells in the gills. Freshwater fishes have the opposite problem and have relatively large kidneys to excrete the water entering their body by osmosis. To offset the loss of salts, freshwater fishes can obtain salts from their food; many also have salt-absorbing cells in their gills and mouths. They drink very little water and take in very little with their food. Several species, such as the salmon, travel between sea water and fresh water; they therefore have to spend a short period in brackish water to allow their bodies to adapt to the new conditions.
Marine fish live in a medium of greater concentration than their body fluids; this means that they tend to gain salts by diffusion and lose water by osmosis. To offset the loss by osmosis, they drink sea water, most of which their kidneys are able to retain – the salt is excreted, often through special cells in the gills. Freshwater fishes have the opposite problem and have relatively large kidneys to excrete the water entering their body by osmosis. To offset the loss of salts, freshwater fishes can obtain salts from their food; many also have salt-absorbing cells in their gills and mouths. They drink very little water and take in very little with their food. Several species, such as the salmon, travel between sea water and fresh water; they therefore have to spend a short period in brackish water to allow their bodies to adapt to the new conditions.
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23 December 2001, 01:58 PM
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But how do they know how much they have drunk? I mean, if i have a pint of beer, then i can see how much i have drunk by looking how far down the glass the head is.
Fish, on the other hand, don't have glasses, so must estimate how much beer they have drunk. We all know (especially Mellow!) how hard that is
mb
Fish, on the other hand, don't have glasses, so must estimate how much beer they have drunk. We all know (especially Mellow!) how hard that is
mb
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