Wednesday, October 21, 2009 ; Science Question
Michelle has emailed me regarding respiratory system of fish.
The process (out of syllabus) goes like this:
1) The mouth of fish opens to let water with dissolved oxygen enter.
2) The gill cover opens (mouth closes) and water gushes out of the gills. As water gushes out, the gill filament (red area below the gill cover) absorbs the dissolved oxygen and releases carbon dioxide to the water.
All you need to know is that fish breathes through gills and breathes in dissolved oxygen.
Dissolved oxygen is formed when:
1) Oxygen enters the water from the water surface. (Oil will prevent oxygen from dissolving into water from the surface)
2) Water plants photosynthesize and give out oxygen to the water. Oxygen will then dissolve into the water.
One thing you need to take note is that dissolved oxygen is not visible, meaning you will hardly notice much bubbles.
Also, when fish breathes near the surface of the water, it is breathing in oxygen that dissolves at the surface of the water. It cannot breathe in atmospheric oxygen like humans can.
As for circulatory system of fish, it is totally out of the syllabus. Like humans, fish has a heart to pump blood to enable gas exchange. Gas exchange is performed at the gill filaments (the red area when you lift up the gills of fish).
Only those in bold and brown are in your syllabus. I hope the above information helps.
Posted by Mr Wan
posted by Allan at
10:43 PM
6 Comments:
Yeps, they do help.
Thanks, Mr Wan ^^
hey mr wan... that means if like my fish tank the air pump make bubbles come out right, the bubbles are dissolved oxygen? so when like we shake the water bottles then the water got bubbles that is dissolved air?
Air pump does not oxygenate the water. It speeds up movement of water to the surface of the water for oxygen to dissolve in water. The bubbles you see are actually carbon dioxide and nitrogen mainly.
Uneven water surfaces speed up the exchange of gases at the water surface, so air pump does that too. Putting plants like hydrilla is even better as it photosynthesizes and causes water surface not to be even.
As for shaking of water bottles to create bubbles, those bubbles are caused by air trapped by the "waves" you created in the bottle. As the "waves" collapse rapidly back to the water, air cannot escape in time and becomes "bubbles" in your bottle.
All these I've mentioned, by the way, are not in your syllabus but are extremely interesting knowledge to share.
thank you mr wan, and so, air pump is no use one arh? people buy air pump for what? erm.. for my tank hehe. i don't know.. l0l tks for your info and it's rather interesting to know about these facts.
mr wan, is there a way to remember all these??? >.< because, i still dun understand...
Just remember fish breathes in dissolved oxygen and dissolved oxygen is formed when oxygen enters the water surface. Aquatic plants photosynthesise to give out dissolved oxygen too.
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