Invertebrates represent over 95% of animal species and contain the vast majority of individual animals on Earth, yet their welfare is almost entirely unregulated and poorly understood.
Invertebrate welfare represents both the most morally urgent and the most scientifically uncertain frontier in animal welfare. The combination of extreme numbers, emerging sentience evidence, and almost complete regulatory absence means this is an area where science and policy are dramatically misaligned. The precautionary approach - applying welfare consideration where sentience is plausible but uncertain - argues for meaningful attention to invertebrate welfare now, before scientific certainty is achieved. Consumer, advocacy, and research attention to invertebrate welfare can shape what becomes an enormous moral challenge.