Characterizing resting periods in Neohelice granulata to identify sleep-like behavior in an intertidal animal

Sleep is a fundamental biological process conserved across animals and known to be regulated by homeostatic and circadian mechanisms. Although sleep has been extensively studied in several animal models, including invertebrates, it remains unexplored in intertidal animals, whose activity is potentially shaped by tidal cycles. We recently reported that the semiterrestrial crab Neohelice granulata exhibits a prolonged period of low activity from morning through early afternoon, characterized by a “resting” posture (low cephalothorax, tucked in claws) guided by an endogenous rhythm, suggesting the possibility of sleep-like behavior. Using DeepLabCut for automated behavioral analysis, we are testing whether sleep deprivation induces a compensatory increase in resting behavior, as predicted by sleep homeostasis. We are also assessing whether the arousal threshold to mechanical stimulation differs between active and resting crabs. We aim to identify specific postural patterns associated with immobility and reduced responsiveness, and to determine whether these postures increase following sleep deprivation. Together, these behavioral criteria will allow us to evaluate whether N. granulata exhibits sleep and provide the first characterization of sleep-like behavior in an intertidal animal.