1. The effects of a Depressant on the Pulse Rate of Lumbriculus Variegatus Introduction : In this experiment we studied the pulse rates of Lumbriculus Variegatus, otherwise know as the Blackworm. The blackworm is a very small invertebrate that is found in shallow ponds, rivers, and marshes. They are a good candidate for testing, because they are exposed to many chemicals in their habitat. Also, blackworms can be easily reproduced in labs through asexual reproduction called fragmentation, because the worm has very rapid regeneration. The skin of the blackworm is very transparent, which allows the pulse to be counted without harming or entering into the organism. Hypothesis: If the blackworms are exposed to the water with depressant, then their pulse will be slower than the pulses of the spring water worms. Independent Variable: The water with the depressant Dependent Variable: The worms pulse rates per minute Control: The worms in the regular spring water Constants: o Worms (type, age and size) o Time under light o Containers they were kept in o Temperature of water o Maintained use of spring water, not tap water Materials: o Microscope o Worms in depressant o Worms in spring water o Well- slides & cover-slips o Pipettes o Stopwatch By Katy Perry and Jayne Bannister Procedure: We set up our microscope and ensured that the light was working. Then, we got the worm on the slide and put the cover slip on. Next, once the slide was on microscope we viewed its pulse rate. We used our phones to count out a minute and then recorded our findings. This process was repeated for all trials. Observations: “These worms are the craziest and most mobile I have ever dealt with”- Mrs. Climenhaga o As the worms heated up under the light of the microscope, they became more energetic, and likewise, the cooler they were the calmer they acted. o As the quote states, these worms were very active and naughty, like little kids. o We got to use homemade well- slide for viewing. o The worms had a beautiful dark red pigmentation Results: Our results were very interesting. As a whole, the depressant worms did have slightly lower pulse rates than the spring water worms, with one exception, in trial 5. This worm had a pulse rate of 22 pulses/ min. We are going to view this trial as an outlier/ fluke and omit him from the final average. The final average for the depressant water worms is 12.7 pulses/min. The spring water worms had a smaller and more consistent range of pulses compared to the blackworms from the depressant water. The average pulse rate of the spring water worms is 16.9 pulses/min. Conclusion: After analyzing the data we have collected, we believe that the results do back our hypothesis. The depressant water worms did have slower pulses than the spring water worms. The only aspect that calls this into question is trial 5 of the depressant test, with 22 pulses/ min, which was omitted from the final average. We believe that the worm was probably slightly too big for the well and should not have been used, especially to preserve our constants. Also, we might have had him out of the water slightly longer than the other worms. C. Drewes. 2004. Lumbriculus variegatus : A Biology Profile http://www.eeob.iastate.edu/faculty/DrewesC/htdocs