Harmful effect of ethanol for the invertebrate daphnia. Essay

Ethanol is known as a toxic and harmful substance to the human body (Ascencio & Mittal, 2010), which is a vertebrate. However, the experiment clearly proves that it is also harmful for the invertebrate daphnia. Ethanol with concentration of 95% was immersed to daphnia solution on the microscope slide. This showed that the daphnia's movement increased although its heart rate decreased (Ascencio & Mittal, 2010). Ethanol causes nerve cells in the daphnia's body to bind differently thus affecting its heart rate in different ways, a high concentration caused the death of daphnia (Ascencio & Mittal, 2010).
Sucrose is a simple carbohydrate, which act as an energy when consumed by humans (Cocks, 2000). Similarly, when daphnia feed on sucrose, it acts as energy for them. Sucrose with a concentration of 1% was immersed to daphnia solution on the microscope slide. As shown in table 1, it increases their movement. Sucrose was also found to increase their heart rate as in the process of digesting the sugar, the heart needs to beats faster to keep up with the oxygen needed for them to digest (Cocks, 2000).
Daphnia did not display any chance in response when it was immersed in room temperature tap water. Daphnia has an optimum temperature of 18C to 22C (Elenbaas, 2013). By immersing daphnia in 5C temperature, it decreases their movement and some of the daphnia eventually stop moving. This is because their metabolic rate decreases with the decrease in temperature and they would not become active until they absorbed heat. The metabolic rate decreases because many enzymes are less active when temperature decreases and the reactants inside the cell have less thermal energy. Thus, the enzyme slows down in 5C and the daphnia may die (Gerritsen, 1982). In table 1, it is shown that hot water with a temperature of 55C causing them to increase their movement. Although as stated above, daphnia has an optimum temperature of 18 to 22C (Elenbaas, 2013). Therefore, it should have killed daphnia when they were introduced to hot water. This occurrence of introducing daphnia to hot water is due to the fact that different species of daphnia reacts differently. The daphnia species used in the laboratory is unknown.
Daphnia has an optimum pH level between 7.2 and 8.5, although pH 6.5 and 9.5 is still suitable for them (Dieter, 2005). When pH 3 was immersed to daphnia, it shows that it increases their movement. This is due to severe acid stress and the activation of defense mechanism (Weber & Pirow, 2009). Acidic water condition was found to be harmful to fish and crustaceans such as daphnia (Haines, 1981). As it could make them suffer from physical and skeletal deformity (Haines, 1981). When pH 10 was immersed to daphnia, it shows that its movement decreased and eventually some of them died. It is found that pH affects their reproductive system (Vijverberg, 1996). It is also found that in pH 10, poor condition of daphnia can be observed, as they eventually died (Vijverberg, 1996).