Embedded Files
Repeat steps 6-7 19 times, so that 20 planarians are bisected.
Keep 10 planarians whole and untreated.
Take initial measurements and photographs of all planarians, including whole and bisected portions.
Transfer the planaria into their respective petri dishes.
Cover the petri dishes with their lids.
Store the baking sheet with the petri dishes in a dark, cool place.
Photograph, take measurements, and change the water of the planarians every two days over a two-week period.
Take final measurements.
Data Tables:
Using a scalpel, make a horizontal cut halfway through the planarian, resulting in two equal head and tail portions (bisection).
Transfer a planarian onto the ice.
Place several cubes of ice on the plate.
Using a pipette, transfer the planaria from the jars onto a styrofoam disposable plate.
Pour spring water into each dish.
Place 6 petri dishes on the metal baking sheet and label each with its corresponding group of planaria and magnets. The plates should be placed over their respective group of magnets.
Arrange the magnets accordingly on a baking sheet.
Procedure:
Hypothesis: I hypothesize that magnets will affect the regeneration rate of a planarian flatworm by reducing its regeneration and growth. I also predict that the anterior (head) portion of a bisected planarian will regenerate faster than the posterior (tail) portion. I based my prediction that magnets will slow down the regeneration rate of a planarian on the fact that prolonged exposure to high-strength magnets can indeed be harmful to many organisms. For example, long-term exposure to an MRI (Magnetic Resonance Imaging) machine can potentially be harmful to humans. Naturally, I would assume that planaria would be similarly affected by high strength neodymium magnets. I predicted the head portions would regenerate faster than the tail portions because the head portion contains a planarian’s eyespots and mouth, which help it navigate, and a tail seems like it would be easier to regenerate than something as complex as an entire head.
Problem: Planaria, yet so seemingly simple creatures, are one of the most fascinating animals on Earth. Planaria are a type of non-parasitic flatworms that live in most bodies of both freshwater and saltwater, including lakes, ponds, and rivers. They possess the astonishing ability to regenerate their body parts after being cut into two or more parts. In fact, a single planarian can be cut into a maximum of 279 pieces, and each portion would regenerate as a full-size planarian in a few weeks. Planaria are able to accomplish this phenomenal feat by utilizing the abundance of pluripotent stem cells contained in their bodies. These type of cells are able to be reprogrammed to meet any need the planaria may have or to replace any cells that have died or separated. This inspired the idea for my science fair project. I decided to conduct an experiment to discover whether exposing planaria to high strength magnets would have any effect in its regenerative process and if the anterior and posterior portions of a bisected planarian regenerated at different rates.
By: Obed Pelaez
During my experiment, I made and recorded many interesting observations. First of all, I noticed the planaria were small creatures, approximately 10 mm. in size. Their black skin appeared very slimy, covered in some type of mucus. They had an arrow-shaped head with two flat eyespots. They moved by wriggling their body and whipping their tail around in the water. The planaria are very inactive and immobile until you move them, causing them to react to their surroundings quickly.
When I bisected the planarians, I had also observed many interesting things. I noticed that the planaria would move in shallow water by contracting their bodies. Naturally, this made it difficult to bisect and make an even cut across their bodies. I placed the planaria on an ice cube and this alleviated the issue, causing the worms to slow down. I also noticed that in order to make a good cut, I had to hold the scalpel down across the body or else the cut would heal itself within seconds.
I was also able to make many observations when the planaria were growing inside their petri dishes. The first thing I noticed during this stage of the experiment was that the tail portions would not move at all in the water, while the head portions were very active,able to move freely even after they were bisected. The head portions also tended to stick to the walls of the petri dishes, while the tail portions preferred to remain in the middle of the dish. Additionally, at the beginning, the head portions were regenerating much faster than the tail portions, but once the tails portions had regenerated their heads, their regeneration and growth increased substantially. It wasn’t until the eighth day of testing that the tail portions of the planaria had regenerated their head and began moving often. The last observation I made was that near the end of testing, the head and tail portions were almost indiscernible from each other. It was very difficult, if not impossible, to distinguish which planarian had started as a tail portion or a head portion. I relied on my prior measurements to help me distinguish which planarians were which.
Graphs and Observations:
Materials:
2 Jars of Live Planaria
6 Petri Dishes
21 Strength 1 Neodymium Magnets ( 7/16" dia. x 1/32" thick) (Pull Force=1.24 lb.)
21 Strength 2 Neodymium Magnets (7/16" dia. x 1/16" thick) (Pull Force=2.61 lb.)
42 Strength 3 Neodymium Magnets (7/16" dia. x 1/16" thick) (Pull Force= 3.23 lbs.)
Ruler
Scalpel
Pipette
Ice
Camera
Bottled Spring Water
Baking Sheet
Conclusion:
After analyzing and and carefully examining my data, I have made several conclusions. First of all, I have come to the conclusion that my data has fully contradicted my hypothesis. I had hypothesized that magnets would affect planaria by decreasing its regeneration rate and overall growth, but this prediction was entirely inaccurate. My data has shown than in almost all tests, exposure to magnets correlates directly with the regeneration rate of a planarian. In essence, the exposure to stronger magnets results in greater and quicker regeneration in a planarian. This claim can be supported by the data I have collected. The Group 1 planaria, which were bisected and exposed to no magnets, experienced an average regeneration amount of 2.2 mm. over a two week period. The Group 2 planaria, which were bisected and exposed to strength one magnets, had an average regeneration amount of 2.8 mm. The Group 3 planaria, which were bisected and exposed to strength two magnets, demonstrated an average regeneration amount of 3.8 mm. The Group 4 planaria, which were bisected and exposed to strength three magnets, had an average regeneration rate of 4.8 mm. per two weeks. The Group 5 planaria, which were untreated and not exposed to any magnets, had an average growth of 2.6 mm. Comparatively, the Group 6 planaria, which were untreated and exposed to strength three magnets, showed an average growth of 2.8 mm. This proves not only that magnets can increase the regeneration rate of a bisected planarian, but that stronger increments of magnets result in greater regeneration rates. Additionally, it is demonstrated that magnets can not only help a bisected planarian grow, but they can also increase the regular growth of a whole planarian. I predict that this result occurred because magnets, in some way, stimulate the growth and regeneration of planarians, perhaps stretching the bodies of the planaria within the strong magnetic field. The second part of my hypothesis was also proven incorrect. I had predicted that the anterior portions of bisected planaria would regenerate faster than their posterior counterparts; however, I discovered they both regenerated at approximately the same speed and to the same extent. This conclusion is completely supported by my data. In Group 1, the head portions regenerated an average amount of 2.6 mm., while the tail portions regenerated at an average of 1.8 mm. Similarly, in Group 3, the anterior portions regenerated an average amount of 3.6 mm, while the posterior portions regenerated an average amount of 4 mm. This shows that there is not one definitive portion or half that regenerates faster than the other. The reason behind this result is simple. For the most part, the head and tail portions were equal in length, so they would naturally regenerate roughly the same amount. This also proves that regenerating a head is no more a difficult task than regenerating a tail. I believe my experiment was very accurate, as I tested a variety of magnet strengths, repeated my tests often, and kept all variables I wasn’t testing constant throughout the duration of the experiment. If I could have improved upon the design of my experiment, I would have also included other species of planaria to see if they regenerate differently or at different rates.
Abstract:
My project was designed to discover whether there is a correlation between the intensity of a magnetic field and the regenerative process that occurs in planarian flatworms. Planaria are non-parasitic flatworms that live in freshwater ponds, streams, and lakes. They possess the remarkable ability to regenerate when cut into two or more parts. I used three strengths of magnets for my experiment: Strength 1 Magnets, Strength 2 Magnets, and Strength 3 Magnets. The planaria were separated into six groups: Group 1 with bisected planaria and no magnets, Group 2 with bisected planaria and strength one magnets, Group 3 with bisected planaria and strength two magnets, Group 4 with bisected planaria and strength three magnets, Group 5 with untreated planaria and no magnets (control), and Group 6 with untreated planaria and strength three magnets. I hypothesized that magnets would have a significant impact on the growth of a bisected planarian by decreasing its regeneration rate and also that the head portion of the bisected planarian will regenerate faster than the tail portion. Before I began my experiment, I had to prepare my materials. First I organized my magnets on a metal baking sheet according to the respective group of planaria and magnet strength. Next I poured spring water into six empty petri dishes. I proceeded to transfer the planaria from their shipping container into a plate with ice, using a pipette. I used a scalpel and bisected 20 out of 30 planaria over ice, to slow their movement and prevent their contraction. Subsequently, I used a ruler to measure the lengths of each planaria portion. Lastly, I photographed the planaria and placed them in their corresponding petri dish: 5 sets of head and tail portions were placed in Groups 1-4 (each dish), while 5 whole planarians were placed in Groups 5 and 6 (each dish). I measured, photographed, and changed the water of the planaria every two days for a period of two weeks. The data I collected demonstrated that magnetism had a profound impact on the regeneration rate of planarian flatworms. The Group 1 planaria, which were bisected and exposed to no magnets, had an initial average length of 4.9 mm and a final average length of 7.1 mm., indicating an average regeneration growth of 2.2 mm (per worm). Comparatively, the Group 4 planaria, which were bisected and exposed to the Strength 3 magnets, had an initial average length of 5.3 mm. and a final average length of 10.1 mm, resulting in an average regeneration rate of 4.8 mm. over a two week period (per worm). This proves that using high strength magnets can increase the regeneration rate of a planarian flatworm by 2.6 mm. on average. My data also indicated that the head and tail portions of a planarian regenerate at roughly the same rate. The Group 1 planarian head portions had an average initial length of 5.2 mm., while the tail portions had an initial average length of 4.6 mm. The final average measurements for the head and tail portions were 7.8 mm. and 6.4 mm., respectively. The head portion regenerated 0.8 mm. more than the tail portion,suggesting a faster regeneration rate. However, the difference is so insignificant that it cannot be concluded that either portion regenerates faster than one another. I also observed that once the tail portions had regenerated their head, their growth increased substantially. The results of my experiment have completely contradicted my hypothesis. The prediction that the head portions of the planaria would regenerate faster than the tail portions was not very accurate, as they regenerated at approximately the same rate. Additionally, I had hypothesized that the magnets would slow down the regeneration rate of bisected planaria, but this turned out to be incorrect. In fact, it was the complete opposite. Exposing a bisected or whole planarian to magnets resulted in a faster regeneration rate and better overall growth. I suspect this occurred because the magnetic fields may stimulate growth and recovery in the planaria. I believe my experiment was very accurate, as I collected a large amount of data and tested various strengths of magnets; however, planarian contraction may have affected the accuracy of my measurements. By conducting this experiment, I have realized the importance of testing your hypothesis because as probable as it may seem, there is always the chance that it could be incorrect.
Page updated
Report abuse