Caffeine In Blackworms

Introduction:

With over nine hundred and seventy one tons, the United States is the country with the highest amount of caffeine consumption in the world. This chemical compound is known to have many affects on our bodies, primarily in our hearts. Caffeine has been shown to increase blood pressure and heart rate. However, as far as scientists know, the affects of caffeine may affect invertebrates differently than it affects vertebrates. The present experiment studied blackworms - Lumbriculus variegatus in the phylum Annelida- in solutions with different amounts of caffeine to see if it affected their pulse under a compound microscope. Worms do not have hearts; they have aortic arches that contract to push the blood into the dorsal and ventral

blood vessels. Under a compound microscope, the contraction of the aortic arches is visible, and by counting how many times one arch opens and closes in the course of sixty seconds is considered the heart rate. The purpose of this experiment is to see how different amounts of caffeine affect the pulsation rate in black worms. If blackworms were exposed to different amounts of caffeine, then the worms exposed to the higher amounts of caffeine will have a higher pulse rate than those exposed to lower amounts of caffeine.
Methods:
To study the influence the amount of caffeine has on the pulsation rate in blackworms, three worms were placed in each of the three petri dishes labeled accordingly to the amount of caffeine contained in each dish. Each petri dish contained 40ml of water. In one of the petri dishes, two tablets (100mg) of Natrol Caffeine Fast Dissolving pills were dissolved in the water. In another petri dish, one tablet (50mg) of the same type of caffeinated pills was dissolved in the water. Finally, the third petri dish contained no caffeine whatsoever to show the pulsation rate of blackworms in normal conditions. After leaving the worms in the solutions for 5 minutes, they were placed under a compound microscope and their pulsation rate was recorded for thirty seconds. Taking this rate and multiplying it by two, their beats per minute were recorded. To ensure the most precise results, this was repeated once more with fresh worms.
Data:
Trial 0mg 50mg 100mg
Trial 1 19 bpm 12 bpm 19 bpm
Trial 2 20 bpm 13 bpm 14 bpm
Trial 3 15 bpm 11 bpm 16 bpm
Trial 4 18 bpm 14 bpm 20 bpm
Trial 5 21 bpm 13 bpm 18 bpm
Trial 6 17 bpm 11 bpm 14 bpm
Average 18.3 bpm 12.3 bpm 16.83 bpm

Figure 1: Amount of Caffeine Affecting Blackworm’s Beats Per Minute
Conclusion:
This experiment was designed to show the effects caffeine has on their pulsation rate in blackworms when placed in solutions with different amounts of caffeine.

I predicted that the blackworms in higher caffeinated solutions would have higher pulse rates, because caffeine is known to increase blood pressure and heart rate. However as far as scientists know, invertebrates are not expected to have a strong response to caffeine like vertebrates do. Also, caffeine in low doses is known to lower pulse rate. The results do not support my hypothesis. The results show that when black worms are placed in caffeinated solutions, their pulse rates on average are lower than those placed in a solution with no caffeine. A possible flaw that may have occurred during experimentation is that the petri dishes were not properly cleansed, or that there were other properties in the water that influenced the outcome. To eliminate these flaws, I could have boiled the petri dishes and water to insure that there were no other properties to influence the data. Further experimentation should be performed with higher doses of caffeine to further insure that caffeine does in fact lower their pulse rate. The insufficient number of trials performed lead to less confidence in my conclusion that caffeine lowers the heart rate in

blackworms.