The question of pain in invertebrates has profound implications for how we treat billions of animals daily.
Invertebrates represent the vast majority of animal life on Earth. If they experience pain — even in a simplified form — the scale of suffering caused by practices affecting them is almost incomprehensibly large. The scientific debate is genuine: nociceptors exist across the animal kingdom, but whether they generate subjective experience of pain is uncertain. Applying a precautionary principle — reducing unnecessary harm to invertebrates where practical — seems warranted given the stakes.