A transfer pipette was used to place a single Daphnia magna into the well of a concave slide and any excess water was removed by using a Kimwipe tissue. The use of a coverslip was unnecessary so that the specimen isn’t crushed and killed. The D. magna had enough water to allow its gills to function but not so much that it could’ve actively swim. The specimen’s heart was located using a light microscope using the lowest magnification.
We determined the baseline heart rate by allowing the organism to adapt on the slide for 5 minutes. A marker and paper was used to count the beats since the heart rate was going too fast. We then counted the number of heartbeats for 5 seconds, using a timer. We multiplied that number by 12 to estimate the
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As a control for the experiment, a drop of spring water was placed on to the specimen. Once again, the specimen was allowed to acclimate for 5 minutes. Then we obtained the heart rate just as it was done before. This was done with a total of 3 different D. magna.
For the green tea portion of the experiment, we determined the baseline heart rate by allowing the organism to adapt on the slide for 5 minutes. We then counted the number of heartbeats for 5 seconds, using a timer. We multiplied that number by 12 to estimate the heart rate in beats per minute. The heart beats were counted for 5 seconds, then a drop of green tea was placed on to the specimen. Once again, the specimen was allowed to acclimate for 5 minutes. Then we obtained the heart rate just as it was done before. This was done with a total of 3 different D. magna.
For the black tea, we determined the baseline heart rate again by allowing the organism to adapt on the slide for 5 minutes. We then counted the number of heartbeats for 5 seconds, using a timer. We multiplied that number by 12 to estimate the heart rate in beats per minute. The heart beats were counted for 5 seconds, then a drop of black tea was placed on to the specimen. Once again, the specimen was allowed to acclimate for 5 minutes. Then we obtained the heart rate, which was done with a total of 3 different D.