How is there a moral imperative? Could you explain it?
To take an example ranking of potential food animals: fish, chickens, cows, pigs, great apes, humans.
There's a question about where you draw the line, but most people agree there is one. Few people think it's OK to eat chimps.
It's not clear on this hierarchy where octopuses fit in.
No, intuitively, most people do not agree there is a line… people just buy meat and eat it, and the main consideration is taste. Can you provide any evidence suffering factors into the majority of peoples food decisions?
That just seems so bizarrely naive to me. Every living thing suffers when hurt. Suffering is a feeling of not wanting to die, or to be hurt. I'm pretty sure that it is one of the primary mechanisms of evolution of living things, it is a strive for self preservation. Human suffering is fundamentally the same as that of an octopus, an insect or a tree.