• Brine shrimp egg cysts
• Sheet of graph paper 3 cm _ 4 cm
• Magnifying glass
• Pair of forceps
• Bright light
• Fine glass pipette
• 40 cm3 beaker of salt water
Procedure
1. Decide on a range of temperatures from 5 °C to 35 °C to be tested.
2. Place 2 g of sea salt into a 100 cm3 beaker.
3. Add 100 cm3 of de-chlorinated water and stir until the salt completely dissolves.
4. Label the beaker with the temperature at which it will be incubated.
5. Place a tiny pinch of egg cysts onto a large sheet of white paper.
6. Wet the square of graph paper using a few drops of salt water. Dab the paper onto the white sheet to pick up about 100 eggs. This will look like a tiny shake of pepper. Use a magnifying glass to count the eggs. Cut the graph paper so that there are exactly 100 eggs.
7. Put the paper with the 40 eggs into the beaker (eggs-side down). After three minutes, use a pair of forceps to gently remove the paper, making sure that all the egg cysts have washed off into the water.
8. Repeat steps 2 to 7 for all the temperatures that are to be investigated.
9. If possible replicate the treatments.
10. Incubate the beakers at the appropriate temperatures.
11. The next day count the number of hatched larvae in each of the beakers. To do this, place a bright light next to the beaker. Any larvae will swim towards the light. Using a fine glass pipette catch the brine shrimps and put them in a small beaker of salt water. Repeat the counting daily for several days. Brine shrimps are very delicate and care must be taken when handling them. Finally, release the young brine shrimps into a salt water aquarium.
12. Record the number of larvae that have successfully hatched at each temperature.
Results
Evaluation
When looking at the results that I have obtained I can see that when the temperature increases to about room temperature and about 30, many of them will hatch here. For example at the temperature at 5ºC, there was no shrimps that had hatched but when se look at one of the 30ºC we see that it can go up to 12 of them that have hatched. When it goes above 30ºC, however, the number again decreases to near enough 0. My results including the groups may not be very reliable as there is not a very distinct observation that I can comment on as they all look spread out. If I was to draw a graph for this I would see that there would be little if any correlation.
When doing this experiment in particular we have to look at some issues that are ethical and by this I mean when testing shrimps for the use of science. I had decided that it was ok that we used these eggs for the sake of science as it may help us in the future. We will also release these back into the water once we have finished with them. The ethical issues will be mainly brought up when we start carelessly using a higher number of shrimps than we needed.
In every experiment, only the reliable and accurate results are useful. The more of these we do and taking an average we will be able to get a fairly good result and because we used the class results I believe that normally this is going to be a highly reliable experiment. This may not be the case when we get errors from places and so to get an even better result we should look at the results and take out some of the anomalous results.
An example of an anomalous result is that I had got a result that is very different from the others. For example if we got a high number of shrimps that had hatched and then in one of the tries we see that there is not any that had hatched, then this will be anomalous. We could blame this on systematic errors. As I have mentioned before we may only have 100 shrimps. If we exceed this number then we might find that there are errors due to that the space occupied by each shrimp egg is too small. Another error is that we do not know that the room temperature is constant and if we left it over a couple of days we may have found that the temperature at night may not necessarily be the same as it was in the day.