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The Effect of Zinc on Worms
Da'Jhnae Gambrell-Sanders
Sustainability and Conservation 1H
DSHA
February 26, 2016
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Abstract
The purpose of this lab is to determine if earthworms are capable of detecting high
levels of zinc in their environment. In order to test this, worms were placed in the middle of
four quadrants, each containing a different concentration of zinc.The worms were then
observed for twenty minutes to see which quadrants they decided to burrow in. Our results
show that the worms would burrow into a quadrant at random and would remain inside that
quadrant for the full time period. These results support the theory that worms cannot initially
detect harmful substances within the soil, which furthermore can have harmful ramifications
on our environment as well as the food chain.
Introduction
Environmentalists have made the argument that insects and other animals that reside in
the soil are not able to avoid chemicals used by farmers and manufacturers. Two experimental
labs were conducted at Divine Savior Holy Angels High School to test this argument; a simple
sensorimotor reaction lab and a preference avoidance behavior lab. With the first lab, worms
were placed in low, medium, and high concentrations of zinc and data was recorded on what
types of reactions the worms had. Zinc is a natural substance found in the environment and is
necessary for life and our environment. However, zinc in the environment has been rising
unnaturally due to human activities such as mining and steel processing. (Lenntech, 2016) Zinc
is beneficial for the human body to function in reasonable doses; however, high levels of zinc in
the human body are incredibly toxic and can lead to many health risks. Symptoms of zinc
poisoning include: chills, convulsions, fever, low blood pressure, vomiting, shock, and yellowing
of skin or eyes (National Library of Medicine, 2016). Therefore, because of this build up in the
environment and its health risk factors, zinc was used in this experiment. What was concluded
after the experiment is that when the worms were placed in low concentrations of zinc, they had
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little to no reaction to it. However, as the zinc concentration increased, the worms would have
stronger reactions on initial contact. The second lab that was conducted was that a worm is
placed between two lines of liquids; a line of water and one line of highly concentrated zinc. The
experiment was conducted to see if red worms were able to sense the liquids and make the safest
decision and choose to cross the water line. On all attempts with a different worm used in each
attempt, the worms each chose the zinc. Therefore, it was concluded from both experiments that
worms are affected by chemicals in the environment and they are not able to sense and avoid
them. But will the results from the previous experiments hold true when red worms are placed in
a natural soil environment with multiple concentrations of zinc? To test this, a lab was conducted
using three different concentrations of zinc; 10 ppm, 100 ppm, 1000 ppm, and one control group
of distilled water in four different quadrants of soil. The locations of the worms will then be
timed to see how much time they spend in each quadrant. If the Earthworm is placed in the
middle of these four quadrants over twenty minutes, then the Earthworm will initially enter the
medium and high concentrations of Zinc but will retreat and spend most of its time in the lower
concentrations because our second lab proved that the Earthworm was unable to recognize the
difference between the line of water and the line of zinc.
Materials and Methods
Materials:

Pipets

Latex gloves

Safety goggles

Dissecting tray

Red worms
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
Potting soil

10 ml. each of zinc solutions of 10 ppm, 100 ppm, 1000 ppm

Distilled Water

Stopwatch
Methods:
1. Gather all materials; divide lab tray into four quadrants using your finger and label
each quadrant by number as well as mark which quadrant will have which
concentration of zinc or water as shown here in Figure 1 and Figure 2:
Figure 1: Soil Quadrant setup)
Figure 2: Zinc Concentration Quadrant setup
Quadrant One
Quadrant Two
( 10 ml. 10 ppm)
Quadrant Three
(10 ml. 100 ppm)
Quadrant four
(10 ml.1000 ppm)
(10 ml. distilled water)
2. Place on goggles and gloves; distribute potting soil evenly amongst the quadrants
3. Take pipet and measure 10 ml. 10 ppm of Zinc into quadrant one (Reference Fg. 2)
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4. Take pipet and measure 10 ml. of the 100 ppm of Zinc into quadrant two (Reference
Fg. 2)
5. Take pipet and measure 10 ml. of the 1000ppm of Zinc into Quadrant three
(Reference Fg. 2)
6. Take pipet and measure 10 ml. of distilled water into quadrant four (Reference Fg. 2)
7. Place the worm in the center of tray so that it is positioned in the middle of the
quadrants
8. Record which quadrant the worm enters first and begin timer for twenty minutes
9. In those twenty minutes, record how much time the worm spends in each quadrant
using your notebook and pen
Data Tables and Graphs
Minutes Worm Spent in Each Quadrant:
Days
1
2
3
4
Quadrant 1
(10 ppm)
0 minutes
0 minutes
0 minutes
0 minutes
Quadrant 2
(100 ppm)
0 minutes
20 minutes
0 minutes
20 minutes
Quadrant 3
(1000 ppm)
0 minutes
0 minutes
20 minutes
0 minutes
Quadrant 4
(10 ml. Water)
20 minutes
0 minutes
0 minutes
0 minutes
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Which Concentrations Did the Worm Enter Each Day?
25
Minutes
20
15
10 ppm
100 ppm
10
1000 ppm
Control (10 ml. of Distilled Water)
5
0
Day 1
Day 2
Day 3
Day 4
Days
Percentages of Time Spent in Each Quadrant
Quadrant 2
Quadrant 3
Quadrant 4
Quadrant 1
0%
25%
50%
25%
Results
In this experiment, there are three types of variables. The first one is the independent
variable which include the different concentrations of Zinc in each quadrant. The dependent
variable was the amount of time the earthworm spent in each quadrant. The control variables
were the amount of soil in each quadrant as well as the amount of solution in each quadrant.
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While on each day of experimentation the worms had the choice of which quadrant to enter in,
on days 2 and 4, the worms decided to enter into Quadrant 2, which contained a medium zinc
concentration of 100 ppm; to add to that, the worm spent 50% of the experiment in this quadrant
over the four days. Also, all of the earthworms spent their 20 minutes in the quadrant they
initially decided to burrow into. Figure 1 below shows where the worm was placed at the
beginning of each experiment trial. One trend that was seen is that out of the four days of
experimentation, the worm spent time in three out of the four quadrants; these quadrants
included the distilled water, medium, and high zinc concentration quadrants.
Figure 1:
Figure 1:At the beginning of each trial, the worm are placed in the center of the tray so
they have an equal chance of picking one of the four quadrants.
Discussion
To conclude, our data failed to support our hypothesis. We had originally thought that the
worm would enter the medium to high concentrations and then retreat to low concentrations.
While we were correct that the worm spent most of its time in Quadrants two and three,
specifically 75% of experiement time, however on each of those days the worm would spend the
full twenty minutes in those quadrants instead of moving to a lower concentration upon
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exposure. However, while our hypothesis was not supported by our data, this lab was able to
further prove that worms cannot initially sense pollutants in the soil as they made no effort to
avoid the high concentrations of zinc. In regards to possible errors in our experiment, we added
less solution, about 5 ml. of solution, in each quadrant which may have affected our results from
day one because 5 ml of zinc may not have been as potent on the worms as with a higher dosage.
Soil pollution can negatively affect the metabolism of microorganisms and arthropods, which
can destroy some layers of the primary food chain and have a harmful effect on predator animal
species. Also, small life forms may consume harmful chemicals in the soil which may then be
passed up the food chain to larger animals, which may lead to increased mortality rates and even
animal extinction (Everything Connects, 2016). The pollutants can be passed on from consumer
to consumer throughout the food chain and can increase the concentration as move up into the
higher trophic levels which could potentially affect our health, as well.
Further Questions
Our experiment observed and tested whether earthworms can detect different concentrations of
zinc in soil and if they can, does that affect where they choose to live and burrow. After
completing this lab, one major question emerges; How does Zinc affect the worm’s bodily
functions, specifically its nervous system over a prolonged amount of time?
Works Cited
"Office of Dietary Supplements - Zinc." Zinc — Health Professional Fact Sheet. N.p., n.d. Web.
25 Feb. 2016.
"Soil Pollution." Everything Connects. N.p., n.d. Web. 25 Feb. 2016.
"US Environmental Protection Agency." US Environmental Protection Agency. N.p., n.d. Web.
25 Feb. 2016.
"Water Treatment Solutions." Zinc (Zn). N.p., n.d. Web. 25 Feb. 2016.