MadSci Network: Environment & Ecology

Re: how can i test for physiological processes of the Artemia & Daphnia?

Date: Wed Dec 9 11:20:15 1998
Posted By: Rob Campbell, Grad student, Biological Oceanography, Dalhousie University
Area of science: Environment & Ecology
ID: 908672072.En

Hi Beth-

That's a bit of a tricky question! There are many many processes that go on inside an organism which can be considered "physiological processes". For instance, respiration, excretion, the storage and usage of food in the body, and the production or hormones can all be considered to be physiological processes, and those are just a few examples! Artemia is used by a lot of scientists, and there is a lot known about its physiology. However, most of the techniques used by those scientists are pretty complicated, and beyond the means of your average high school student (well, I haven't been in high school for a while, so I don't know what you have in your labs nowadays!)

For what they're worth, here's a couple of simple ideas:

  1. Both Artemia and Daphnia have circulatory systems. That means that they have hearts: I'd say that the simplest physiological measurement you could make would be heart rate. You'll have to keep the animal more or less immobile- basically the smallest container you can find. Then, either under a microscope, or with a magnifying glass, look at the animal closely- you should be able to see the heart along it's "back" beating away rather quickly. To count the heart rate, you simply need to count the number of beats within a known time frame, say a minute, or 30 seconds. Someone to keep track of time while you're counting might be handy. You could try this with various treatments simulating different strengths of acid rain, and see if there's a difference.
  2. Another easy to measure quasi-physiological parameter you could try would be swimming speed- Artemia are smooth swimmers, so their speed will be difficult to measure (though you could maybe videotape them and calculate it from that, if you have access to a video camera.) Daphnia, however, swim in a series of "hops" and you could count the number of hops it makes in a fixed time period (much like with heart beats) and use that as an index of swimming speed.

Hope that helps,
Rob Campbell, MAD Scientist

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