This project is concerning the effect of caffeine on Daphnia’s heart rate. Daphnia is known as the water flea. Daphnia is a very small aquatic crustaceans and its body is divided into three main parts. Its heart is large and their skin is partially see-through. So it is easy to count the heart beat. In this experiment, place a daphnia onto a slide with a few drops of water and take its resting heart rate. After a number of trials add a solution with caffeine onto the slide and then take the heart rate again. Count the heart beat for 10 seconds and multiply the number by 6. When adding coffees to the slide, count the heart rate for 5 seconds and multiply the number by 12. Then take the average of each solution. The conclusion of this project is that coffee, Community, had the most effect on daphnia’s heart rate. The average heart rate for Community was 272 beats per minute.