This is from an op-ed someone wrote, and my view tends to agree. However, I am happy to hear other points of view:
"Moreover, since oysters don't have a central nervous system, they're unlikely to experience pain in a way resembling ours—unlike a pig or a herring or even a (broken link removed). They can't move, so they don't respond to injury like those animals do, either. Even monkish ethicist Peter Singer sanctioned oyster eating in
Animal Liberation —the best-argued case for a vegan diet I've read—before reversing his opinion for later editions of the book. To justify the flip-flop, he wrote that "one cannot with any confidence say that these creatures do feel pain, so one can equally have little confidence in saying that they do not feel pain." This is unconvincing: We also can't state with complete confidence that plants do, or do not, feel pain—yet so far Singer hasn't made a stand against alfalfa abuse.The main argument of
Animal Liberation is that discriminating against nonhuman animals is indefensible because it makes irrelevant category distinctions—pain cuts across species barriers. But to loop oysters into a dietary taboo simply because we've labeled them animals is to make just such a faulty distinction. Likewise, we shouldn't be eating more plants
because they are in the plant kingdom; we should eat them because it's a sound way to feed ourselves without causing a lot of damage to the world. And oysters, as far as we can tell, belong with plants in almost every ethically relevant way"