Thread: experiment

Hi everyone we have to design and carry out an experiment on

do fish attack groups of daphnia or just individuals.

we are provided with 5 fish , 5 tanks, tank dividers, boiling tubes, a sieve, pipettes and stop watchers.

IF it was you how would you do this what would be the best way to set and carry this out , any ideas welcome .

Thank you.

why do you post the same message here and under 'Experiments' when you already had a reply under 'General Discussion' ?

also, why are you making us do your homework for you? you tell us how you would do it, and we'll tell you what we think.

I am not asking for you to do it i was just asking for some good ideas. I was thinking of dividing the tanks up into 3 spaces 1 with low density one with medium and 1 with high and see how long it took for the fish to eat them ?

that wouldn't answer your question. It would answer the queston: does the fish eat higher density prey more efficiently than lower density prey. And actually maybe it doesn't even do that. Unless you time the event and then scoop out all daphnia from each tank and weigh them, comparing it with their weight before. If it is easier to eat in higher density you would expect that they have eaten more from the high density tank.

If they eat more from a low density tank I guess you have some kind of proof that maybe they get less confused with fewer individuals.

You need a good scale though. And I don't know if the fish will eat enough for you to be able to measure the difference.


And otherwise, like i said before in another thread. You need to start with defining things. What is an individual daphnia. What constitutes a group. Observe daphnia in the tank. Do they go distribute into groups and individuals. Could you use that as a basis for measuring behaviour.

Observe the behaviour. Make sure you can write down quickly what the fish is doing. Or videotape it. Break down the behaviour in steps.

Fish hovers. fish moves towards. Fish eats single daphnia. fish moves towards single daphnia, towards group. etc.

Put it in a graph. Can see see if they prefer attacking groups or individuals.

I think i havea rough idea on what im doing now but how would i represent it in a graph and then anylize statisticly ? what wud be the best statistic method to use ?