View Full Version : Saltwater fish not salty?
12-04-2000, 11:56 AM
When I eat a saltwater fish, why doesn't it taste salty? Wouldn't a fish tend to have a concentration of salt similar to the surrounding water?
12-04-2000, 12:11 PM
Active transport and Passive transport (osmosis) are involved here. It is easier for the fish to try to lose its own water in an attempt to dilute the ocean. Of course, evolution/God/whatever works in such a way that the fish has means of keeping this all in check.
Knowing what muchrooms are grown in, why don't they taste like shit?
12-04-2000, 12:15 PM
No. In general stuff on the outside stays on the outside. Carrots don't taste like dirt.
Salt is sodium cloride. Unless the fish had a reason to store sodium cloride, you would not taste salt. If either the sodium or the cloride was used, and the other expelled, you would not taste the salt.
12-04-2000, 01:15 PM
This is actually pretty complicated. A fish's relationship with its environment is not at all analogous to a mushroom's or a carrot's to its growth medium.
Fish have a very direct, interconnected osmotic relationship with the surrounding water: their gill membrane is an osmotic filter through which oxygen and other dissolved elements pass freely. Most fishes' osmotic balance with their environment is very precise and precarious: most saltwater fish will die fairly quickly in freshwater, and vice versa. Saltwater fish, having evolved in an extremely stable environment, have evolved fewer mechanisms for adjusting to instability, and are generally more susceptible to chemical (or any other) fluctuations in the water in which they live.
When I was running my aquarium business, I could have explained this in more detail. I'd be happy to search out some information, but won't have time to do so until later.
Meanwhile, here's (http://www.aqualink-too.com/ubb/board/Ultimate.cgi) a discussion forum that might help you.
12-04-2000, 05:27 PM
I often give talks to grade school kids and one of the most common questions is "do fish drink water?" The answer is complicated and interesting, and related to your question. Saltwater fish and freshwater fish have about the same amount of salt in their bodies, and this is similar to most other complicated animals on the earth. This concentration is about the concentration of the early seas where life originated. All of our enzymes and body processes started with that baseline, and thus they stay. The oceans are saltier now, so they are saltier than the fish. Water tends to move over membranes toward the higher concentration of salt (osmosis), so freshwater fish are constantly urinating to get rid of the extra water, while saltwater fish dink a lot of water and excrete the salt through specialized organs on their gills. One of the biggest energy demands on fish is osmoregulation, or control of their salt content. One of the marvels of nature is that some fish can go back and forth between salt and fresh, which must be a nightmare to their systems.
The exceptions to this rule are the sharks and rays, who beef up their internal salinity by the retention of urea. Somehow they are able to withstand huge concentrations of this normally toxic substance. This also accounts for the strange smell of fresh shark meat.
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