Well, we might just have to rethink every crab leg feast ever (as delicious as they are). A new study from Queen's University Belfast found that crabs actually might feel pain, and that could apply to all crustaceans.
Researchers at the Queen's School of Biological Sciences tested 90 crabs, offering them two dark caves in a bright tank. "Crabs value dark hideaways beneath rocks where they can shelter from predators," Professor Bob Elwood says. "Exploiting this preference, our study tested whether the crabs experienced pain by seeing if they could learn to give up a valued dark hiding place in order to avoid a mild electric shock."
One of the caves would shock a crab upon entering, while the other wouldn't. Researchers found that after two rounds of shocks, crabs learned to avoid that specific shelter. In fact, sometimes they were willing to leave their cave if it shocked them in order to search out the other cave.
The level of pain which the crabs might feel is still unknown; "On a philosophical point it is impossible to demonstrate absolutely that an animal experiences pain," Elwood says. The study, however, has data that is consistent with "the idea of pain," and the results show that there is a strong probability of pain.
This revelation is particularly nervewracking, as a common way to cook crab and lobster is to stick them in a pot of boiling water while still alive. Others argue that the most humane way to cook crustaceans is to take a knife down the back of the head, killing them immediately. It's not for the faint of heart, and the ethical dilemma remains. (But it's delicious! But they feel pain! It can go on forever).