The opposite effects of caffeine and ethanol on Daphnia magna’s heart rate

Abstract

Caffeine is used in everyday life for many to achieve the feeling of alertness; however, when ethanol (alcohol) is consumed the adverse effect is expected. Studies have varying results on how heart rates are affected when either caffeine or ethanol are introduced. We proposed that when caffeine was added to a solution, the heart rate would increase, and when ethanol was added to a solution, the heart rate would decrease. We first observed Daphnia magna heart rate under a slide in aquarium water, and then again after adding either solution to the water. We expect that our findings will be of interest to regular caffeine and/or alcohol consumers in understanding how these substances can increase or decrease heart rate in the short term.