It always was a very soothing way of thinking for humans cooking crabs and lobsters alive. They were told the sea animals didn’t feel any pain. But now research suggests otherwise. Even with their hard shells and different brain structure, the sea creatures don’t like to get hurt.
It may never be possible to really prove what happens in the mind of animals when they suffer. Still, British researchers tried. They made a distinction between reflexes and actual pain. In their view reflexes serve to avoid immediate tissue damage, while pain can alter animal behavior to avoid damage in the future.
To test the crab’s ability to feel pain the researchers put them in a brightly lit tank with two dark shelters to hide, which shore crabs like to do. In one of the shelters the crabs were give electric shocks. After two trials the crabs started to avoid the electric dark shelter, instead choosing the less painful one.
This rapid learning to avoid electric shocks, shows crabs indeed feel pain, the researchers conclude. If you’re not convinced yet: another way of proving the experience of pain in animals was done in 2009. Norwegian researcher gave fish a burning sensation, not damaging any tissue.
One group of fish received morphine just before they were exposed to the painful sensation, the other group didn’t. Both groups of fish reacted by wriggling during the sensation, but afterwards only the non-drugged fish acted wary.
What can we make of this? The researchers say the altered behaviour of the non-morphine fish shows they actually felt pain, as opposed to the fish that suffered less, because of the morphine.
The two studies definitely prove that pain-like stimuli can alter animal’s behavior, making them avoid the stimuli in the future. But this strictly doesn’t say anything yet about what goes on in the mind or consience of these creatures. So it’s still up to you what to believe next time you push a hook through a fish’s lip or throw a living crab into boiling water.
Magee, B., & Elwood, R. (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 (3), 353-358 DOI: 10.1242/jeb.072041