The effects of Alcohol on the pulse rate of the Lumbriculus Variegatus
By: 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 solution
Dependent Variable: Pulse rate of blackworms
Control: Worms exposed to spring water
Constant: 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
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
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.
Data: We recorded the pulse rate for each worm in
the different solutions for one minute.
.1 Mm
.5 Mm
10
12
11
10
12
11
14
14
15
9
1 Mm
10
11
12
17
9
11
10
12
13
11
Spring Water
20
23
22
18
18
27
21
20
20
19
13
10
14
11
12
16
12
11
12
12
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.