Lumbriculus Variegatus Introduction Lumbriculus Variegatus also known as the California blackworm can be found throughout North America and Europe living in shallow water where it is easy for them to feed on decaying vegetation and microorganisms The blackworm reproduces asexually ID: 661743
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The Effects of Depressants on the Pulse Rate of Lumbriculus Variegatus
IntroductionLumbriculus Variegatus, also known as the California blackworm, can be found throughout North America and Europe, living in shallow water where it is easy for them to feed on decaying vegetation and microorganisms. The blackworm reproduces asexually by means of fragmentation, meaning it breaks itself into smaller pieces and those pieces then regenerate the lost parts until they are full blackworms again. Lumbriculus Variegatus has no heart but instead pumps blood through its body with rhythmic pulsations of its blood vessels. This pulse starts at the tail end ,where gas exchange occurs, the makes its way to the head. This experiment attempts to answer the question, “How do depressants affect the pulse rate of a blackworm?”. The blackworm makes such a good test subject because it has very thin, transparent skin making it easy to see its pulse rate under a microscope.
HypothesisIf a blackworm is exposed to a depressant then its pulse rate will decrease.
VariablesIndependent: DepressantDependent: Pulse Rate
Materials2 identical containersSpring waterDepressantBlackwormsMicroscopePipetteRecovery bowl
Results
The data shows that the depressant decreased the pulse rate of the blackworms. The comparative graph shows that the average pulse rate of blackworms in spring water is 20.4 pulses per minute and the average pulse rate of a blackworm that has been exposed to a depressant is 15.6 pulses per minute.
By: Jacob
Squicciarini and Isabella Cox
ObservationsWe had to cut a smaller well so the worm wouldn't move around as much. When counting the pulse it was easiest to count when looking at the center of the worm. If the worm was left on the microscpe too long it would move around, making it difficult to see the pulse. The depressed worms looked like they were fragmented and regenerated recently.
Method 1) Once the worms have acclimated to the spring water, add a depressant to one dish. 2) Count the pulse rate of multiple blackworms from each dish by watching the pulse go through the worm under the microscope over a certain period of time. Be sure to record the data from each dish. 3) After the worms have been observed place them back into the recovery dish. 4) There should be ten trials.
Conclusion The hypothesis agrees with the data collected. The pulse rate is lower when there is a depressant than compared to the spring water. In order to improve the experiment each group should have their own set of worms. By having your own worms there is less chance of another group accidentally causing stress on the worm if it's left under the microscope to long.
Data
Resources
Drewes
, CD. 2003. A toxicology primer for student inquiry: Biological Smoke
Detectors. The Kansas School Naturalist, Emporia State University,
50(1);3-14