Circadian Rhythms of the Spider Pholcus phalangeoides in Activity Monitors and Web Boxes

Circadian rhythms are endogenous molecular clocks that correspond to the 24-hour day and are regulated by light stimulus, allowing organisms to entrain to the dawn-dusk cycle. These clocks may allow organisms to anticipate daily events, influencing their behavior. In arthropods, including spiders, circadian rhythmicity is tested using activity monitors, which house individuals in tubes. However, this does not reflect the natural habitat of many spiders. We compared the locomotor activity of the cellar spider Pholcus phalangiodes in activity monitors with the locomotor activity in web boxes. After being entrained to a 12:12 light:dark cycle, the spiders were recorded in constant darkness. The resulting free-running periods demonstrated similar clock data for spiders in tubes as in boxes. This validates the activity-monitor research method