The effects of Alcohol on the pulse rate of the Lumbriculus VariegatusBy: Mallory Broda & Andrea Aman

Introduction: Lumbriculus variegatus, also known as a blackworm, are used for many experiments by scientists. This is because they’re transparent, which makes it easy to observe bodily functions, such as pulse rate. They are also unique because the effect of drugs can be observed in a short period of time. Lumbriculus variegatus has a closed circulatory system, meaning it doesn’t interact with other systems. These worms are found throughout North America and also Europe, on the edges of pond, lakes and marshes. We are testing these worms to see if alcohol has an effect on the blackworm’s pulse rate. Alcohol is a colorless flammable liquid that is the intoxicating component in beer, wine, spirits, and other drinks. It is also used as a industrial solvent and fuel. Alcohol is a depressant drug that slows down thinking, reaction time, and has effects on the brain and spinal chord. We chose to test the effects of alcohol because it is widely used around us.

Hypothesis: If a California Blackworm is exposed to an alcoholic solution then its pulse rate will decrease when compared to blackworms exposed to spring water.Independent Variable: Alcoholic solutionDependent Variable: Pulse rate of blackwormsControl: Worms exposed to spring waterConstant: Temperature, containers, well slide, type of blackworm, transport method

Materials: Petri dish, blackworms in spring water, blackworms in alcohol, microscope, well slide, stop watch, thin stem pipette graduated cylinders, flasks

two minutes. Record time each was exposed to the solution. After ten minutes retrieve worm from solution with thin stem pipette and place into well slide, of the lowest power, record each worms pulse rate for one minute using microscope. Replace the tested worms into the petri dish with two new worms from spring water. Repeat this until all 10 worms are tested. Once their pulse rates are tested, place them into the fourth petri dish filled with spring water to recover. Observe how and if the blackworms recovered.

Observations: We exposed blackworms to the concentrations for 20 minutes. There were 10 worms in each petri dish. After each exposure time was up, we used a thin stem pipette to touch each of the worms to see if they would recoil. We found that in the .1 Mm concentration all of the worms had good reflexes. In the .5 Mm concentration 50% of the worms had good reflexes. In the 1 Mm concentration only 10% of the worms had good reflexes.

Results: When the blackworms were exposed to an alcoholic solution for ten minutes, their average pulse rate per minute was higher than the blackworms exposed to spring water. The average pulse rate per minute of the blackworms in the alcoholic solution was 20.8 . The average pulse rate per minute for the blackworms in spring water was 12.3. Surprisingly the worms exposed to the higher concentration of alcohol had a higher pulse rate than the worms in the lower concentrations. However, there wasn’t a big difference in the pulse rate per minute of the worms exposed to the .1 Mm, .5 Mm and spring water.

Conclusion: We concluded that our hypothesis was incorrect. When the blackworm was exposed to an alcoholic solution, the pulse rate per minute significantly increased, instead of decreased like we expected, since alcohol is a depressant. The only discrepancy in our experiment was that the .1 Mm, .5 Mm, and the spring water solutions all had very close average pulse rate, while the 1 Mm solution was almost double all of the others. From observing the worms behavior, everything went as expected. We found that in the .1 Mm concentration all of the blackworms had good reflexes, in .5 Mm only 50% had good reflexes, and in 1 Mm only 10% of them had good reflexes.

Procedure: Obtain four petri dished and one weight boat. Fill three petri dishes with one of the solutions, place two blackworms from room temperature spring water with thin stem pipette into each petri dish every

Data: We recorded the pulse rate for each worm in the different solutions for one minute.

.1 Mm .5 Mm 1 Mm Spring Water10 10 20 1312 11 23 1011 12 22 1410 17 18 1112 9 18 1211 11 27 1614 10 21 1214 12 20 1115 13 20 129 11 19 12