Ms Chortyk told one correspondent that she checked with the BC SPCA's Head of Animal Health (Dr James Lawson) and the Canadian Federation of Humane Societies (an old boys' network of the big players in the animal welfare business) and they both assured her that crabs have no central nervous system. The only conclusion one can draw from that statement is that the SPCA believes that makes it okay to boil crabs alive. My understanding, though limited, is that there doesn't have to be a central nervous system, just nerve cells, for pain to be felt. But perhaps crabs have no nerve cells.
Perhaps the BC SPCA trained vet, Dr Lawson, can explain why Dr. Nedim Buyukmihci, professor of veterinary medicine at the University of California, Davis is wrong when he says, "It is, therefore, completely rational and biologically sound to state that crabs would be able to feel pain. Moreover, their behavior is consistent with this principle.”