The science of invertebrate pain and sentience is advancing rapidly, with implications for how we consider the welfare of billions of insects, crustaceans, and other invertebrates.
Invertebrate welfare science is at an inflection point: the question has shifted from whether invertebrates have nociceptors (they do) to whether they have subjective pain experience. Cognitive bias experiments with bees and crabs suggest emotional state effects consistent with pain. The welfare implications of positive answers are enormous — insect and crustacean use in food, research, and pest control affects trillions of individuals annually. The precautionary welfare principle argues for minimising invertebrate suffering proportional to probability of sentience — which is now non-trivial for many species.