Crustaceans Can Feel Pain Just Like Vertebrates

If you've justified dropping lobsters into boiling water alive on the grounds that it doesn't feel pain the way vertebrates do, or stuck a knife into a living crab while preparing it under similar justification, well, you were wrong.

Some new experiments carried out Robert Elwood, of Queen's University Belfast, hopefully put an end to the notion that crustaceans of all sorts don't actually feel pain, and that any movement away from unpleasantness they encounter is just a reflex response, not up to the standards we've created for vertebrates, and that we're just anthropomorphizing.

The Nature News Blog reports that Elwood has demonstrated that shore crabs learn to avoid shocks, actively choosing shelter spots on repeat visits where there is no risk of shock. He's also shown that "hermit crabs [can] make motivational trade-offs as a result of pain"—again, with electric shock being the painful stimulus.

Based on his study of shore crabs, published in the Journal of Experimental Biology, Elwood and co-author Barry Magee conclude (emphasis is mine) the "data are consistent with key criteria for pain experience and are broadly similar to those from vertebrate studies."

Here's how pain is defined for the purposes of the study: "An aversive sensory experience caused by actual or potential injury that elicits protective and vegetative reactions, results in learned behavior, and may modify species-specific behavior. [Animals in pain should] quickly learn to avoid the noxious stimulus and demonstrate sustained changes in behavior that have a protective function to reduce further injury and pain, prevent the injury from recurring, and promote healing and recovery."

Elwood told attendees at an animal behavior conference in the U.K. that his experiments show these animals have "clear, long-term motivational change that is entirely consistent with the idea of pain." This is to such a degree that if we were talking about mice, we'd stop killing crustaceans in awful ways.

How long before research such as this filters down into general knowledge and animal welfare laws get changed is anyone's guess. Considering how poorly vertebrates are treated just because we can make tasty things with them, it's likely to be a long time.

Example: One Italian town passed a ban on the boiling of live lobsters (calling it "useless torture") back in 2004, along with a whole host of animal welfare protections. Following Godwin's Rule of Nazi Analogies, at least one discussion of said law managed to reference Hitler's vegetarianism and regulation of cooking lobsters in just two comments. Like I said, it unfortunately will be a while before there's general acceptance that in many crucial ways humans and other animals are very much alike.