As David Foster Wallace argued in Consider the Lobster, a recent study indicates that lobsters feel pain, an unpleasant finding for an animal that's often boiled alive. But as Wallace says:
Is it possible that future generations will regard our present agribusiness and eating practices in much the same way as we now view Nero's entertainments or Mengele's experiments? My own initial reaction is that such a comparison is hysterical, extreme -- and yet the reason it seems extreme to me appears to be that I believe animals are less morally important than human beings; and when it comes to defending such a belief, even to myself, I have to acknowledge that (a) I have an obvious selfish interest in this belief, since I like to eat certain kinds of animals and want to be able to keep doing it, and (b) I haven't succeeded in working out any sort of personal ethical system in which the belief is truly defensible instead of just selfishly convenient.