Pill Bugs And Crickets Lab Report

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The purpose of this experiment was to measure the metabolic rate of pill bugs and crickets. I indirectly measured the metabolic rate of each organism by calculating their respiration rates. In crickets, gas exchange is accomplished via a tracheal system [Contreras, Bradley, 2010]. Pill bugs have pleopods, gill-like respiratory organs [Gibbs, Smigel, 2008]. My hypothesis was that the crickets will have a faster respiration rate than the pill bugs. I used a respirometer to measure the oxygen consumption of pill bugs and crickets. After plotting the data, I used the slope to obtain the respiration rate. The respiration rate per gram of organism for the pill bugs was 0.0025 mL/min./g. The respiration rate per gram of organism
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Pill bugs, Armadillidium vulgare, are terrestrial isopods [Gibbs, Smigel, 2008]. Thus, they are not very well adapted to land [Gibbs, Smigel, 2008]. Water loss is a reoccurring theme because terrestrial isopods lack “cuticular lipids and the elaborate spiracular apparatus of insects” [Gibbs, Smigel, 2008]. Most of the water loss is evaporation from the respiratory organs [Gibbs, Smigel, 2008]. The respiratory organs are called pleopods, and are gill-like organs “located on the ventral abdominal segments” [Gibbs, Smigel, 2008]. Interestingly, pill bugs are capable of conglobation, the ability to roll up in a ball [Gibbs, Smigel, 2008]. In addition to protection from predation, conglobation may also conserve water [Gibbs, Smigel, 2008].
In this experiment, I will be comparing the metabolic rates of two different species. Because they are two different species, and differ in physiology, I will expect to see a difference in metabolic rate. More specifically, I expect crickets to have a higher metabolic rate, due to their efficient respiratory system.
Materials and Methods:
The lab handout provided by the instructor was used as a guideline to conduct this experiment. The only difference was the organism used and data collection period. For this experiment, pill bugs and crickets were utilized. Also, data was collected for a period of 12 minutes.

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