Audrey Kentz
Demos
Honors Biology
11/04/15
The Effect of Different Concentrations of Ethanol on Earthworms for an Allotted Exposure Time
and How Long it Takes Them to Begin to Burrow
Abstract
In this experiment, we investigated to see if longer exposure to different concentrations of
ethanol solutions effects how long it takes a worm to start to burrow in soil. The test exposed a
worm to a concentrated solution between two cups, then after an allotted amount of time, the
worm was placed on soil and timed to see how long it took to start burrowing. Based on what
was concluded, it does affect burrowing time. The major trend that was in our data was that the
longer the worm was exposed to the highest concentrated solution, the longer it took the worm to
begin to burrow. This test is very important because it could show what would happen to a
human if they were exposed to too much ethanol. For example, drinking too much alcohol.
Overall, the conclusions showed that if a human, or any other creature, were exposed to too
much alcohol, they would be negatively affected.
Introduction
Our group decided to research and experiment on worms with different concentrations of
ethanol. We exposed the worms to different concentrations for different amounts of time to see if
that affected how long it took the worm to start to burrow. It was decided that this topic is
important since humans are always near or are using ethanol. Our group predicted that if
somehow too much ethanol gets into a human’s system, there will be severe damages. To test
this, the worm is a great model to use because it is so similar to humans. The way that the
worm's nervous system functions with contractions are very similar to the muscle contractions in
humans. Worms are also very easy to study due to the simple structure of their nervous system.
In the research found, ethanol is very prominent in the world that we live in. The substance is
used in cleaning products, gases and fuels, toiletries, medicines, and mostly in alcohol that
people drink (Alcohol, 2015). In fact, beer is approximately 4.5% ethanol (alcohol), wine
consists of 11.6% alcohol, and liquor 37% alcohol (Bryner, 2010). This experiment could
potentially show the effect of too much alcohol on a human body. During a study that was
performed on rats, researchers found that prior exposure to ethanol may contribute to damaging
effects on brain behavior and the ability to survive after a serious brain injury. Two hours after
the rats were induced with 3.0 g/kg of ethanol, severe brain injuries were imposed. Brain
function was recorded daily for one week. The study resulted in rats having a worsened
neurological deficit due to the ethanol exposure prior the the brain injury (Yamakami et. al,
1995). This study on rats only starts to show what the effect of ethanol can do to a simple
earthworm over a designated time of exposure to the substance. In another study, it was found
that when mice consumed ethanol, disruptions in their daily glycogen metabolism occurred. This
results in a disturbance in homeostasis, which could potentially lead to liver disease (Udoh et. al,
2015). Based on prior research found, I predicted that if a worm is exposed to the concentration
of ethanol for the longest amount of time allowed in the experiment, it will take more time to
begin to burrow. This might happen because since the worm is being exposed to the mixture
longer, the worm’s nervous system would be harmed, causing the worm to take a longer amount
of time to recognize it has to start burrowing.
Materials
● 6 clear plastic cups that hold 250 mL
● 36 mL of dechlorinated water
● damp paper towels (dampened with dechlorinated water)
● 18 worms
● 2 pipettes- each able to hold 3 mL
● timers on our phones
● 250 mL of Stein’s potting soil
● 1 mL of ethanol
● 5 - 50 mL flasks
● graduated cylinder (to measure concentrations)
● circular cotton pads
Procedure
1. The worm was placed into a plastic cup filled with 125 mL of potting soil
2. As soon as the worm was placed onto the soil the stopwatch was started. The stopwatch
was then stopped when the worm began to burrow into the soil. (this will serve as the
control group)
3. After the control was found, we set up 5 50 mL flasks with different concentrations
between water and ethanol. We used the graduated cylinder to precisely measure the
substances. One flask was filled with 0% ethanol (just dechlorinated water)
1 mL of stock + 9 mL of dechlorinated water= 10%
1 mL of 10% sol. + 9mL of dechlorinated water= 1%
1 mL of 1% sol. + 9mL of dechlorinated water= .1%
1 mL of .1% sol. + 9mL of dechlorinated water= .01%
4. One cotton pad was moistened with a pipette full of 0% concentration then placed into a
clear plastic cup.
5. The worm was placed directly in the center of the moist pad
6. A second cotton pad was dampened with the same concentration and placed on top of the
worm
7. Another clear plastic cup was placed on top of the second cotton pad to ensure that the
worm would not escape from the chamber
8. When the second cup was placed on top, the alarm was then set for 2.5 minutes
9. The same cup set up was repeated twice more, but the alarm was set for 5 minutes the
second trial and 10 minutes for the last trial (a new worm was used for each time frame)
10. Immediately after the exposure time was obtained, the worm was placed on to 125 mL of
soil in a plastic cup, and the stopwatch was started when the worm touched the soil.
11. When the worm began to burrow (sticks head into soil and keeps digging downwards) the
stopwatch was stopped. (cut off time is 10 minutes)
12. We then recorded time into our data chart
13. The worm was placed on a damp paper towel to keep it moist.
14. The same procedure (4-13) was followed for each concentration, for 2.5, 5, and 10
minutes. Each test was performed with a new worm.
Results
Concentration
Exposure Time
Time it Took to
Percentage
Start Burrowing
Control (no exposure)
Worm 1
Observations
moved head in the air
before burrowing
8.51 seconds
Worm 2
was very still at first
then burrowed
12.06 seconds
wiggled a small
Worm 3
amount before
6.2 seconds
burrowing
2.5 minutes
6. 4 seconds
quickly dug into soil
5 minutes
25.73 seconds
slower reaction, once
0%
the worm began to
move, it burrowed
immediately
10 minutes
33.21 seconds
reacts to container
and slowly
maneuvers into soil
2.5 minutes
19.68 seconds
spent majority of time
crawling around on
.01%
the surface of soil
5 minutes
61 seconds
moved head very
slowly before
burrowing
10 minutes
7.96 seconds
reacted suddenly, and
sped into soil
2.5 minutes
82 seconds
spent most of time
crawling along the
0.1%
sides of the cup
5 minutes
16.5 seconds
was slow in reacting,
but eventually started
to burrow
10 minutes
68 seconds
trying to climb out of
cup, and clung to the
side of the cup for a
while
2.5 minutes
21. 46 seconds
slow start in moving,
began to burrow
1%
eventually
5 minutes
74 seconds
climbed over the side
of the burrowing
chamber, slowly
found way back to
soil and started to
burrow
10 minutes
138 seconds
wormed looked very
flat and dehydrated.
Poked head around
before burrowing
2.5 minutes
41.93 seconds
yellow, puss like
substance left on the
10%
cotton pad, (how
worm reacted to
strong ethanol
solution)
5 minutes
> 600 seconds (> 10
mins)
worm is flat and
completely immobile.
Flat and shriveled
almost like a raisin at
the anterior. Only the
worm’s head began to
move at the 5 min
mark, yet didn’t
burrow until after 10
min. Yellow
substance still
apparent on the cotton
10 minutes
pad
> 600 seconds (> 10
mins)
worm is shriveled up
and curled amongst
itself. completely
still. The worm
SLIGHTLY began to
move its head at 8
min. Began to burrow
way past 10 mins.
In the data chart, the control group, without any exposure to ethanol or water is shown.
The result of our data were scattered. This is due to only having one trial per concentration, per
different time. The last set of data for the 10% concentration shows that the longer the worm was
exposed to the ethanol concentration, the longer time it took the worm to begin to burrow. That
trend is somewhat followed throughout the rest of the tested concentrations.
Graphs
In this graph, the results show how the time it took the worms to start burrowing
increased as the ethanol concentration increased. The outlier would be the time it took to burrow
when exposed to the 0.1% concentration, since the worm took nearly double of the time it took
to burrow when exposed to the 10% concentration. This is a very interesting point in our data. In
the graph, the 0.1% solution data disrupt the major trend.
The graph above still shows the same trend. The outliers are the 0.1%
concentration and the 10%. The worm only took 16.5 seconds to burrow into the soil, while the
other other worms, even the worm exposed to 0% concentration started to burrow slower than
the worm exposed to 0.1% concentration. The worm exposed to the 10% solution took over 10
minutes to start burrowing, which was very long. Again, the 0.1% disrupts the overall trend.
This graph is continuing the familiar trend, except the time it took for the worm that was
exposed to .01% concentration to burrow was surprisingly fast. Overall, comparing the same
percentage of concentration to each different time trial, in the 10% concentration tests, the trend
of taking a longer time to start to burrow when the worm is exposed for 10 minutes is followed.
Within each graph, there was always one outlier that didn’t relate to the overlying trend.
Conclusion
In the experiment, and from the data collected, it was concluded that ethanol definitely
has an effect on earthworms and their behavior. The trend that was apparent in our experiment
was that the longer the worm was exposed to a higher concentration, the longer it took the worm
to start to burrow. Therefore, I accept my hypothesis that when the worm is exposed to a solution
for the longest allotted amount of time, it will take longer to start to burrow. In the 10%
concentration test, the worm that was exposed to the solution for 10 minutes took the longest
amount of time to begin to burrow. Another example would be that in the 1% test, the worm
exposed to the mixture for 10 minutes took the most time to burrow as well. Although before this
experiment, I was convinced that the worms would definitely take a longer amount of time to
start to burrow as the time they were exposed increased. I didn’t expect all the outliers that could
appear in our data and my graphs. But overall, the trend stayed the same. For example, in the
graph where the exposure time was 2.5 minutes, the worms took a very long time to begin to
burrow when exposed to the 0.1% solution. That datum was very different then the results for the
exposure to the 10% solution. The worm started to burrow in half the time then when exposed to
the 0.1% solution. It was also interesting that when worms were exposed to concentrations for
longer times, they didn’t always take longer to burrow. In fact, in some of our data, it was found
that some worms took a shorter amount of time to burrow when exposed to the concentration for
a longer amount of time, rather than a shorter amount of time. Although, there are many factors
that could contribute to an invalid experiment.
Possible sources of error in our experiment include not having more than one trial per
concentration per exposure time, reusing soil so there may have been excess ethanol left in the
dirt, inaccurate timing, using worms that already have been tested on, and inaccurate measuring
of concentrations and potting soil. The major adjustment that would improve our experiment is
to have multiple trials. Having more data will provide a more accurate conclusion and possibly
overrule any outliers. We could also change when we stop and start the timer, such as stopping
the timer when the worm has completely burrowed under the soil.
Additional Questions
This experiment has led me to wonder what cleaning chemicals that contain ethanol and
other harmful substances will do to worms. Since these types of products are commonly used, it
would be beneficial to see the results. I’m wondering if the worms will take a longer amount of
time to react since there would be more harmful chemicals in the cleaning agent than just
ethanol.
Reference Page
● Alcohol. (2015). In Encyclopædia Britannica. Retrieved from
http://school.eb.com/levels/high/article/5513#
● Bryner, M. (2010, July 29). How Much Alcohol Is in My Drink? Retrieved November 4,
2015, from http://www.livescience.com/32735-how-much-alcohol-is-in-my-drink.html
● Effects of acute ethanol intoxication on experimental brain injury in the rat:
neurobehavioral and phosphorus-31 nuclear magnetic resonance spectroscopy studies. I.
Yamakami, R. Vink, A. I. Faden, T. A. Gennarelli, R. Lenkinski, T. K. McIntosh J
Neurosurg. 1995 May; 82(5): 813–821. doi: 10.3171/jns.1995.82.5.0813
http://www.ncbi.nlm.nih.gov/pubmed/7714607
● Udoh, U. S., Swain, T. M., Filiano, A. N., Gamble, K. L., Young, M. E., & Bailey, S. M.
(2015). Chronic ethanol consumption disrupts diurnal rhythms of hepatic glycogen
metabolism in mice. American Journal Of Physiology. Gastrointestinal And Liver
Physiology, 308(11), G964-G974. doi:10.1152/ajpgi.00081.2015
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