"Yikes! At least they can't feel this. Right? Right guys?"
A new study in the Journal of Experimental Biology that is making the rounds on the internet looked at shock avoidance by the shore crab Carcinus maenus. Crabs were placed in a tank with two shelters: one safe and one rigged to shock them. Over a few trials, the crabs avoided the shocking shelter and chose the safe one; by avoiding the shock after trial and error, the crabs were exhibiting a learned behavior from what we, as humans, would perceive as pain. In other words, the crabs learned the one shelter would hurt them while the other one would not, and after a few painful shocks, they would seek out the shelter that wasn't harmful.
a tale of Goldi-crab
This study's results are not so shocking (hey-oh) to me - my snow crabs would consistently massage their limbs after fighting with fellow crabs or reach for their missing limb at the joint when another crab would rip it off. That's why my heart really went out to my dear Legoless.
"I have two legs!" - Legoless in his sanctuary
It's also why I'm so passionate about how I went about sacrificing my snow crabs, and how we prepare Dungeness crabs when we eat them. In a word: QUICK! There's all this "humane" talk about chilling lobsters and crabs in the air for awhile to bring their body temperature down until they stop moving, but, in my mind, that's just slowly suffocating them as they can't breath as well out of water. Also, do you really think an animal who is used to seawater is going to appreciate being on a mass of melting fresh water? I mean, osmoregulation, people.
remember learning about osmoregulation in lyre crabs?
When I had to sacrifice my crabs to measure their gonads, I would take them out of the water, whisper an apology, then swiftly, in one motion, rip their carapaces off of their bodies and remove their heart. Boom. Done. No waiting around for the inevitable. There is this idea of stabbing the lobsters in the heart before boiling, and that may work, but again I'd advise against forcing them to sit on ice just so that you are not so afraid to handle them while they're still active. Man up, people!
Magee, B., and R. W. Elwood. 2013. Shock avoidance by discrimination learning in the shore crab (Carcinus maenas) is consistent with a key criterion for pain. Journal of Experimental Biology 216: 353-358.