Why are controls not needed in the Arthropoda experiment described in the study guide?

Controls are not needed in the Arthropoda experiment if the focus is simply on observing the behavior or characteristics of Arthropoda in a specific environment. In this case, the purpose is not to compare a treatment group against a control group, but to solely observe and record information about Arthropoda. However, if the experiment involves testing a specific hypothesis or comparing different treatments on Arthropoda, then controls would be necessary.