Oysters are about as Primal as you can get. (Much of this post also applies to other shellfish but the focus is oysters.) We have been eating them for at least 125,000 years. Probably longer. During ice age periods, some of our ancestors seem to have hunkered down by the ocean. There are shell middens (piles) wherever humans lived by the sea. See Mark Sisson's discussion.
A self-described vegan, Christopher Cox argues that it is acceptable for vegans to eat oysters. "Biologically, oysters are not in the plant kingdom, but when it comes to ethical eating, they are almost indistinguishable from plants." Naturally, Cox got death threats for saying this. Rigid vegans (redundant phrase) had a hissy fit. But really, why is it OK to kill a plant, which definitely reacts to being killed, but not OK to kill an organism that has no central nervous system? I realize that vegans, and vegetarians, are trying to do what is morally right. But I think they are badly misguided.
Oysters are approved by Monterey Bay Aquarium's Seafood Watch as having minimal impact on marine resources. "And, thanks to the oyster's filter-feeding action, oyster farms can actually benefit the surrounding coastal waters."
Mark writes "Just four medium sized Pacific oysters supply a smattering of B-vitamins (including over 1000% of daily B12), 1200 IU of vitamin A, a third of daily folate, almost 7 mg of vitamin E, 3 mg copper, 280% of daily selenium, and 33 mg zinc. That comes with 18 g protein, 4 g fat, 1.5 g omega-3, 0.1 g omega-6, and 9 grams of carbohydrates." Vegetarians, especially vegans, don't get enough B12, which is abundant in oysters. If they were able to accept that an oyster isn't really different from a plant, they would get the B12 they need.
Actually, the only ways I've had oysters are straight out of the tin, in Cajun dishes, fried or grilled, and scrambled with eggs. I have not had them raw, nor I plan to ever do so. I remember going to the Acme Oyster Bar in New Orleans. Young macho guys were standing at the oyster bar tossing them down. The waiter asked if I was there for "ersters." I said no. Well, I had fried oysters but that wasn't what he meant.