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Name: Phyllis P.
Status: educator
Age: 40s
Location: N/A
Country: N/A
Date: 
Monday, September 30, 2002


Question:
Fish have gills instead of lungs for breathing. Correct? Doesn't this mean that fish are able to get oxygen from the water that they swim in? So this would mean that a fish could survive in a fish bowl provided of course that the water is kept fresh. Correct? Is this true for Betta fish? I read that they have a breathing system called labyrinth which functions similar to human lungs. The article I read said something about them "coming up for air." This sounds strange to me. Is it true?


Replies:
Phyllis,

Many fish can "gulp" air (if you like). Betta sp. and all goldfish, carps are known for this behavior. It is a survival adaptation, and it is found in many other species.

Water carries very little dissolve oxygen in comparison to the atmosphere. Gills are a much better apparatus for taking oxygen out of water than lungs are for taking oxygen out of air. Lungs can afford to be less efficient due to the fact that oxygen is so plentiful in air.

Gills work on an elaborate system of moving water over its intricate blood vessel arrangement to draw out as much of the limited oxygen supply out of the water. Gills have one drawback, they must be kept moist for their membranes are thin and susceptible to drying out, thus destroying the tissues.

Ok, why did I tell you all of this! Gills will work in taking oxygen out of air, actually, better than lungs! If a fish gulps air in polluted or poor oxygenated water, the gills can do just fine, IF kept moist.

Many adaptations have evolved to support fish and gas exchange. Yes, the labyrinthiform organ found in some fish behind the gills can indeed be used to store air for periods of time. However, there are many other arrangements in different species that do the same thing in different ways. Most fresh water boney fish have air sacs that they fill and empty that serve as a means to move deeper or shallower in water without effort, like a submarine. This organ also serves a breathing function in many fish.

So the answer to your question is YES!

Steve Sample


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