Animal Behavior and Physiology in Daphnia
... observe and measure the heart beating. Since daphnia are cold-blooded animals, their metabolic rate is closely related to the temperature of their environment. When it is warm, the metabolic rate increases and when it is cold, it slows down. Using this information, if the heart rate doesn’t change (ie. Remains the same in room temperature and cold temperature), we predict that the daphnia’s heart rate will decrease as the temperature of the bath decreases and will increase as the temperature increases. Materials and Methods: For this exercise, a small piece of foam (containing a well) will be placed in a pastry dish with a drop of water at room temperature. Another pastry dish will be filled with room temperature water. This larger pastry dish is to maintain a constant temperature. The smaller pastry dish will be placed in the larger one. A daphnia will then be placed in the well. The pastry dish will be placed under a dissecting microscope so that the heart rate can be observed. The number of heartbeats could then be counted in a 15-second interval. These steps have to be separated by increasing or decreasing the water temperature. Results: The results of this activity showed that the heartbeat of the daphnia increased as the temperature of the water increased. · See graph in next pages Discussion: In this exercise...