The Onion

Well, the first step to this question is the ever infuriating "define cruelty". It's easy enough with complex vertebrates who have evolved to socially signal pain, which is almost everything we eat. It's even easy to extend it to complex vertebrates which hide pain. But it's hard enough to rigorously say whether something like an invertebrate insect or crustacean even feels pain at all. They certainly have pain responses, but is the qualia of that response in theory internal space recognizable?

It's not an easy question to approach, but it is an important one broadly.