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Allen Sanford and Michael Patterson.
Introduction: The Lumbriculusvariegatus, or blackworm, possesses great scientific value consequent of its unique biological characteristics. Residing in major parts of both North America and Europe, the blackworm can most frequently be observed in marshy areas, or similar places with shallow water, near its favored microhabitats: decomposing foliage, rotting logs, or vegetation near water. The real scholastic significance of the blackworm can be found by observing its closed-circulatory system, made observable by the worm’s transparent skin. Through regular pulsations, the blackworm’s dorsal blood vessel circulates blood and oxygen, via erythrocruorin, the worm’s equivalent to hemoglobin, from the posterior end towards the anterior end. Study of L. variegatus’ pulse rate allows scientists to determine the potential effects a chemical might have on the phylum annelida and humans.
Hypothesis: If a blackworm is given stimulant, the pulse rate will be elevated.
Independent Variable: exposure to stimulant
Dependent Variable: pulse rate
Control: blackworms exposed to spring water
Controlled Variables: ambient temperature, light level of microscope, feeding frequency, relative size of blackworms, worm-handling time
Materials: 4 Petri dishes, 2 Plastic pipettes, Microscope, Cover Slip, Well Slide, Stopwatch, 10 Blackworms, Stimulant Solution Spring Water, Paper Towels
Results: The stimulant group demonstrated a mean pulse rate of 9.2 min-1 higher than the spring water group.
Conclusion: Our results display a statistically significant pulse rate increase in the stimulant-exposed worms compared to the spring-water worms. Conventional laboratory practice requires a p-value of less than .05 for a statistical test to be considered “significant”; in a 2-sample t test, our results demonstrated a p-value of .00554, much smaller than necessary. However, this significance is blind to such possible inaccuracies as the doubling of our thirty-second data and the fact that our control data was collected on a different day than our stimulant data. While not quantitatively affecting the significance, the lab’s results in general are qualitatively weakened by these two impediments. Repeating the experiment with sixty-second trials, more trials per worm, and completion of the procedure unitedly would produce more scientifically viable results.