Identifying changes in activity level in Hemigrapsus nudus under daylight and night conditions

Abstract

Mobile predators in the intertidal zone play a key role in the abundances and distributions of their prey. Hemigrapsus nudus is an ecological generalist found in the intertidal that primarily feeds on green algae. With the constant fluctuation of conditions in their environment, H. nudus must adapt their behavior to better their chances of survival and reproductive success. This study aims to investigate the influence of different environmental conditions on the activity times of H. nudus, particularly comparing daylight and nighttime conditions and the presence and lack of cover. Behavior tracking experiments with no cover present were conducted in the daytime and nighttime, then repeated with cover present. There was no statistically significant difference between the times active in H. nudus in daytime and nighttime but one analysis test found that there may be a statistically significant difference in active times between conditions with cover and without cover present. While my findings stand in contrast with the published literature, there is evidence that crabs exhibit behavioral adaptations in response to their environmental conditions.