Discussion:

Animals take in oxygen and expel carbon dioxide. This is done through a series of metabolic processes. Metabolism is the term given to the set of transformations that take place inside the cells of living organisms. Oxygen is inhaled in respiration while carbon dioxide is exhaled. During this process, other conversions and transformations take place. ATP is formed from ADP glycolysis and then expels energy (Khan Academy, 2009). Useful chemicals are absorbed and used in transformations while carbon dioxide is a by-product formed in these conversions that is not needed. In the Cricket Experiment lab in Bio 102, it was found that field crickets (Gryllus bimaculatus) produced significantly more carbon dioxide than the house cricket (Acheta domestica). There are many reasons that could have yielded this result. Factors such as age, temperature, activity levels, body size, gender and the amount of light could all have resulted in the differences in levels of carbon dioxide produced.
The level of activity is the most obvious factor listed above. As can be seen easily in humans, when exercise or rigorous activity is undertaken our heart rate increases and we breathe faster to take in more oxygen. As a result we also exhale more carbon dioxide. Depending on the differences in the level of activity between field crickets and house crickets, this could have resulted in the findings that were made. It would seem logical to me that field crickets would have a higher level of activity than house crickets because they have a much larger environment. According to the Encyclopaedia of Life Online (2008), house crickets are the most common species of cricket to be found domestically as pets. They are often bred in captivity and their sole purpose is as a pet, or as food to amphibians or small reptiles such as lizards. Because of this, it could be argued that they would have lower levels of activity because they do not need to go in search of food. They also do not have to fear predators, or search as strenuously for a mate to reproduce. House crickets that are bred for domestic purposes are more often found indoors than field crickets are. They would be less exposed in the more sheltered habitats that they reside than the field cricket. In a confined environment, house crickets need to work less in order to survive compared to field crickets.
The level of light could also have an impact on the levels of carbon dioxide. Crickets are a typically nocturnal insect and so are most active during the night (Animal Planet, 2014). In a domestic environment, regardless of whether or not house crickets are kept as pets, it would not often get as dark as it would in the wild. As a consequence of this less nocturnal setting, it could be argued that house crickets are less active. They are never in an environment with an optimum level, whereas field crickets are. Field crickets typically hunt, eat and mate at night time under the cover of darkness. Because of having a good balance of light, and being able to operate under their nocturnal instincts, field crickets could be more active and therefore produce more carbon dioxide. As with light, crickets also have an optimum temperature at which they survive best. Many researchers argue that this temperature is between 27° and 32° Celsius. That is why crickets are most commonly found in hot areas, particularly in late summer and early autumn. The average temperature in a house in Canada is 21° C (Statistics Canada, 2008). This is significantly lower than the optimum temperature required for crickets to be at their most active and have their highest metabolic rates. Being in an environment that has a lower than optimum temperature could cause house crickets to produce less carbon dioxide than field crickets (Hart et al, 2003).
In an experiment undertaken in Norman, Oklahoma, a student concluded from their study that crickets also have an optimum humidity level. From his experiment he argued