How+does+the+heart+rate+of+a+daphnia+magna+change+in+different+types+of+liquids?

Purpose: We are doing this experiment because we would like to figure out how different liquids like soda, energy drinks, and water effect the heart rate of Daphni Magna. Daphnia magna are transparent crustaceans. Their transparent property makes it so you can see the heart rate of the Daphnia Magna through there body. (Ceballos, 2010)

Caffeine in the soda and energy drinks should make the heart beat faster due to caffeine's ability to increase the heart rate. We will look at the Daphnia Magna directly under a microscope since its body is clear we will be able to see the heart. Caffeine is a bitter substance found in coffee, tea, soft drinks, chocolate, kola nuts, and certain medicines. (Caffeine: MedlinePlus) Daphnia magna are relatively easy to obtain, relatively cheap, and consequently lend themselves well to laboratory experimentation. (Switzer) We think that doing this will let us see how the contents of different liquids effect the daphnia magna. We could also base a hypothesis about other animals from these results. Since caffeine is a heart stimulant that raises the beats per minute is should, in theory raise the heart rate. Though there is no way of know that it is the same for every animal until we test it. Caffeine is called a stimulant because when consumed in even small amounts, it will stimulate the central nervous system causing an increased heart rate. (Caffeine) "You can estimate the per minute rate by counting over 10 seconds and multiplying this figure by 6, or count over 15 seconds and multiply by 4, or over 30 seconds and doubling the result"(Measuring). We can maybe use this method to calculate the heart rate of the Daphnia Magna. We could use this to calculate the beats per minute and see its heart rate in water and heart rate in other liquids."Too much caffeine can act to can speed up the heart rate, which can be dangerous for those with diabetes and heart problems.(Meininger) So in this experiment we play to see how caffeine effects a daphnia magna.

Hypothesis: If we give Daphnia Magna a stimulant then its heart rate will increase.

Materials: Caffeine, nicotine, adrenaline solutions, Microscope, Daphnia Magna, and a stop watch, pipet, measurements in bpm.

Procedure: 1. First put the Daphnia magna under the microscope. 2. Then count the number of heart beats per minute with the stop watch. You will be able see the heart rate through its body. This will be the control. 3. Repeat steps 1-2 three times. 4. Fill the pipet with the caffeine nicotine solution. 5. Then put a few drops of the solution on the Daphnia Magna. 6. Put the Daphnia magna under the microscope. 7. Time the amount of beats per minute with the stop watch. 8. Repeat steps 4-7 three times.

Data:
 * < Trial ||< 1 ||< 2 ||< 3 || Average ||
 * < Control Daphnia ||< 200 ||< 160 ||< 250 || 203 ||
 * < Nicotine Solution Daphnia ||< 260 ||< 215 ||< 290 || 255 ||
 * Caffeine Solution Daphnia || 160 || 200 || 200 || 187 ||
 * Adrenaline Solution Daphnia || 150 || 150 || 120 || 140 ||

Analysis: Our control Daphnia Magna had an average heart rate of 203. This is normal for a Daphnia Magna. The nicotine solution Daphnia Magna had an average heart rate of 255. This shows a big increase from the control. The caffeine solution Daphnia Magna had an average heart rate of 187. There is a decrease in heart rate from the control. The adrenaline solution Daphnia Magna had an average heart rate of 140. This is a significant decrease from the control. Overall the control Daphnia had the second highest heart rate which is very surprising. I would think the adrenaline and caffeine would stimulate them more but that might be because we did it over the course of two days. I think average 140 heart rate was so low because it took two days to do. I also think the same about the 187 heart rate. I think the 255 heart rate was perfect. The nicotine increased the heart rate and we did that on the first day.

Conclusion: If we give Daphnia Magna a stimulant then its heart rate will increase. Our hypothesis was mostly accepted with a few exceptions. Some of the solutions decreased their heart rate.

Limitations: Our experiment was done over two days which is not ideal because they can die or get unhealthy in between days. To fix this you should do it over 1 day. It would also be ideal to use a more accurate stop watch because it was almost impossible to get six seconds exactly. Another limitation is that we sometimes couldn't keep up with the heart beat so it would be easier to have a slow motion camera to catch all the heart beats. Our new hypothesis is that if the experiment carries over into the second day, then the heart rate will be slower.

"Caffeine." //World of Sports Science//. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. Vol. 1. Detroit: Gale, 2007. 112-113. //Gale Virtual Reference Library//. Web. 8 Jan. 2013.

"Caffeine: MedlinePlus." //U.S National Library of Medicine//. U.S. National Library of Medicine, n.d. Web. 27 Nov. 2012.

Ceballos, Darrel, et al. "Making the most of the Daphnia heart rate lab: optimizing the use of ethanol, nicotine & caffeine." //The American Biology Teacher// 72.3 (2010): 176+. //Gale Student Resources// //In Context//. Web. 27 Nov. 2012.

"Measuring Your Heart Rate." //Top End Sports.// Topend Sport Network. January 6, 2013. January 8, 2013.

Meininger, Kathryn. "How Caffeine Affects Heart Rate." //LIVESTRONG.COM//. Demand Media, Inc, 24 Nov. 2010. Web. 08 Jan. 2013.

Switzer, Paul V. "Using dragonflies as common, flexible & charismatic subjects for teaching the scientific process." //The American Biology Teacher// 69.3 (2007): 158+. //Gale Student Resources In Context//. Web. 30 Nov. 2012.