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Daphnia: |
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renoufk Member Joined: 19 Jan 2005 No. of posts: 3  View other posts by renoufk |
Posted: 19 Jan 2005 I am using Daphnia to measure heart rate in my Biology coursework, how do you look after them ,what do you feed them? Thanks |
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Caleb Forum Coordinator Joined: 17 Feb 2003 No. of posts: 448 View other posts by Caleb |
Posted: 19 Jan 2005 Daphnia are filter feeders, so you'll need to provide food in suspension. The best food to use is water with lots of algae suspended in it, you might be able to produce this by leaving a jar of water in bright sunlight- the water should turn green as algae grows in it. Failing that, you could use a yeast suspension- just mix some yeast with water. Either way, you should only add a small amount of food to the Daphnia culture, just enough to give their water a slight tint, not enough to make it noticeably cloudy. Lots of fishkeepers culture Daphnia, just google for 'Daphnia culture' or something similar. |
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renoufk Member Joined: 19 Jan 2005 No. of posts: 3 View other posts by renoufk |
Posted: 20 Jan 2005 Thanks |
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jopedder Senior Member Joined: 24 Jul 2003 No. of posts: 55 View other posts by jopedder |
Posted: 24 Jan 2005 I did an experiment measuring daphnia heart rates when I was at school - I was looking at effects of poisons (caffiene, alchohol and nicotine) on heart rates. If this is what you are doing as well take note that at higher concentrations nicotine appeared to kill the daphnia and they had no heart beat, so on these runs I discarded the daphnia into a seperate container, only to find out that they had just been stunned and there hearts started working agoin after a few minutes! - this meant that I had to re-do some of the runs taking this into account. Also remember that as you examine the daphnia under a microscope they will heat from the observation light, increasing heart rate. Good Luck! Jo |
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renoufk Member Joined: 19 Jan 2005 No. of posts: 3 View other posts by renoufk |
Posted: 27 Jan 2005 To Jo, Thank you that is ideal, yes I am measuring the effect of caffeine on the heart rate. Could you possibly tell me the concentration you used of caffeine, as I've seen on a site to use 1% caffeine in water, but am not sure yet how much total volume of water and therefore caffeine should be used- how much did you use per daphnia?! Thanks Katie |
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jopedder Senior Member Joined: 24 Jul 2003 No. of posts: 55 View other posts by jopedder |
Posted: 28 Jan 2005 Sorry Katie, It was about 8 years ago that I did the experiment, and I no longer have my notes. However my mum works in a school prep lab, so I am forwarding your posts onto her to see if she can help. The 1% will be the proportion of caffeine in water, i.e. 99 ml water, 1ml caffeine, therefore the total volume of water is irrelevant. Jo |
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