Sea urchins are harvested globally for their gonads (uni) and increasingly farmed. The evidence for their sentience is limited but their welfare in fisheries and aquaculture deserves consideration.
The welfare capacity of sea urchins is genuinely uncertain. Their nervous system is radially symmetrical and lacks the centralised structures associated with conscious experience in vertebrates. However, they do show nociceptive responses — withdrawing tube feet, spine erection, and avoidance of damaged areas. In fisheries, hand-diving for sea urchins is one of the least damaging harvest methods for the individual animal. Industrial urchin harvesting by dredge causes crushing damage. In areas with urchin population explosions destroying kelp forests, culling programmes are ecologically necessary but their welfare significance is unclear.