Where do you draw the line between animals and plants? Plants are a form of life. Is it the pain? What is it about animal pain that is morally objectionable? Because humans can feel pain too, therefore animal pain is also bad? Assuming we grant that, what if animals were put to sleep before being killed? Does that then make it okay? I find the whole "violence against animals" argument to be incredibly hand-wavy and without substance.
I draw the line in that I don't eat anything with a central nervous system. I don't doubt a biologist might make me reconsider my understanding of a CNS, but I've always found it a clear line for me personally.
