Sea urchins are increasingly farmed for their roe (uni) and show behavioral and physiological responses to stressful conditions that challenge assumptions about invertebrate welfare in aquaculture.
The welfare status of sea urchins is uncertain but not negligible. Their behavioral responses to injury — withdrawal, protective posturing, and avoidance — suggest nociceptive capacity. High-density conditions that impair feeding and cause abnormal aggregation behavior indicate that crowding causes aversive states. As aquaculture volume grows, the uncertainty about sea urchin sentience warrants precautionary attention to density and handling standards.