Whereas circadian rhythms in humans and many other organisms are closely linked to the solar day and even slight deviations could cause significant health problems, several spider species thrive despite extremely shortened or extended circadian clocks. These naturally occurring clocks influence a variety of behaviors, which may help spiders maintain a precarious balance between their conflicting roles as predator and prey. The southern black widow, Latrodectus mactans, is primarily nocturnal in its locomotor activity, but this activity appears only loosely regulated by its circadian clock. This study attempts to determine how internal circadian oscillators affect other aspects of black widow behavior, since preliminary data suggest that they also possess potentially irregular circadian patterns. The behavioral patterns of twenty female black widows were recorded over a span of several weeks. Approximately 3,400 hours of footage in standard (12-hour light-dark cycles) and constant conditions (complete darkness) were analyzed and specific behaviors were recorded using the software BORIS. This study focused on three specific sets of behavior: foraging versus retreat patterns, general activity levels throughout a 24-hr period, and waste disposal. Predation stimuli were also introduced during each cycle set to determine how the widows’ responses were affected by their internal circadian oscillators. Free-run behaviors (behavior no longer entrained to the standard 24hr cycle) observed during the dark-dark cycles differed from the behavior observed during light-dark cycles in both frequency and duration of actions, particularly those related to foraging or web work. Likewise, certain behaviors and prey avoidance techniques observed during light-cycle periods were not observed during constant conditions. This experiment examines several previously unstudied black widow behaviors for generating a better understanding on how they act in natural conditions and to determine how their actions may be influenced by their highly unusual circadian rhythms. Ultimately, this experiment will contribute to a larger, ongoing study investigating circadian-controlled behaviors and rhythms in spiders.

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