Sea urchins are farmed for their gonads (uni) in Japan, Chile, and beyond. Like other echinoderms, their sentience status is highly uncertain — but their ecological importance and production scale warrant careful consideration.
Sea urchin welfare sits at the outer boundary of welfare science's current reach. Their nervous system is even simpler than that of shrimp or crabs, and the scientific consensus on their capacity for subjective experience is that it is very unlikely. The more pressing concerns around sea urchins are ecological: urchin barrens caused by the collapse of predator populations (sea otters, sunflower sea stars) represent ecological welfare disasters for the many species that depend on kelp forests. Controlling urchin overabundance — including through harvesting them for human consumption — can be ecologically beneficial. Aquaculture of sea urchins in tank systems raises the same precautionary questions as other echinoderm production, but at very low probability of causing morally significant harm. The harvest process — cracking the test — is unlikely to cause the kind of suffering associated with crustacean or fish harvest given the absence of nociceptive systems comparable to those species.