David Foster Wallace's famous essay "Consider The Lobster" explores unsettling questions about how much pain lobsters feel when we cook them. By law, that introductory sentence must be on this blog post, which is about new research into whether lobsters and crabs feel pain.
In the Washington Post today, Tamar Stelling has a nice overview of recent work by scientists trying to pin down actual evidence for whether or not invertebrates like crabs, lobsters, octopuses, and squid actually "feel pain," as we understand it. There are plenty of behaviorist philosophers willing to weigh in on this question without knowing a damn thing about neurons, but what the scientists have to say is more compelling:
If he applied a brief electric shock to one part of a hermit crab, it would rub at that spot for extended periods with its claws. Brown crabs rubbed and picked at their wound when a claw was removed, as it is in fisheries. At times the prawns and crabs would contort their limbs into awkward positions to reach the injury. "These are not just reflexes," Elwood says. "This is prolonged and complicated behavior, which clearly involves the central nervous system."
Octopuses and squid also show similar behavior, and possess the same kinds of nerves that detect certain pains in humans. Read all about it here.
It is really not so bad being a vegetarian.