Work was done with: Mickayla Johnston, Dylan Pariseau, and Melissa Wydra.
A medium sized tupperware was used with ½ inch of soil on the bottom. One half of the soil was sprayed with water from a spray bottle (15 sprays). Four isopods were then dropped into the container at the same time, in the middle of the wet and dry soil. They were allowed a 5 minute habituation period. Each minute, the number of isopods in wet or dry soil was recorded. At the end of 5 minutes, the number of isopods in wet or dry soil was also recorded. This data (at the end of 5 minutes) was used in the statistics test to test the hypothesis that isopods prefer to be in wet soil rather than dry soil (If isopods prefer to be in wet rather than dry soil, then after 5 minutes, more isopods will be in the wet soil than in dry.) The null hypothesis is that there is no difference in preference between wet and dry soil for isopods.
The location of the isopods after 5 minutes in wet soil rather than dry is significant with 95% confidence (Mann-Whitney U test– test statistic 15.5 > critical value 15 at P=0.05.) The null hypothesis is therefore rejected.
Figure 1. Mean amount of isopods found on soil types (wet vs. dry) after 5 minutes. Data shows that the mean number of isopods in wet soil after 5 minutes is significantly higher than isopods in dry soil.