In this experiment daphnia magna a semitransparent fresh water crustacean, are used to study the effects of water, alcohol and caffeine on heart rate. Daphnia was placed on a clean deep well slide. This was placed under the microscope and brought into focus on the best objective and light contrast. The heart rate was observed and counted within 15seconds and recorded on a table. Introduction
Daphnia magna is a fresh water ectothermic crustacean commonly referred to as water flea. Because of its transparency we can observe the effects of substances on its body without surgical procedures. We can observe the heart rate of daphnia magna to be dorsal to the backbone just behind the head. (Helms 1998) the average daphnia magna has a heart rate of 180 beats per minute under normal conditions. We will observe the effects of water, alcohol and caffeine on the ectothermic animal. Alcohol is a depressant; this means the body systems will slow down when alcohol is introduced. The heart rate will get consistently lower if too much alcohol is added. Caffeine is a stimulant; this means that it will cause the nervous system to work faster, also it will cause the blood vessels to constrict.(LaFave 2003) These effects will work together to increase an animal’s heart rate under normal circumstances the heart rate will increase as more caffeine is added. Questions
Does changing the daphnia magma’s environment change its heart rate? How will alcohol affect daphnia’s heart rate?
How will caffeine affect daphnia’s heart rate?
Daphnia magna are sensitive creatures and therefore they will respond to slight changes in their environment. Since alcohol is a depressant and can lower human heart rate it should also lower daphnia’s heart rate. Since caffeine is a stimulant it can cause the nervous system in humans to work faster it should also raise the heart rate of daphnia....