26 November 2009

Shell shock: Is the new way to dispatch a lobster a better way?

ResearchBlogging.orgWhen you’re a crustacean neurobiologist, cooking a lobster is a topic you’d better be familiar with, because you will be asked about it. (See posts in February 2005; May 2003; maybe this subject needs to get its own label.)

The Daily Mail has an article on the latest effort to deal with concerns that boiling lobster alive is inhumane. The title claims it’s a way “to kill a lobster with kindness.” This potentially more humane alternative to boiling?


And it’s electrocution with a cutesy name. The device is called “CrustaStun,” which I’ll wager is supposed to be pronounced “cru-stay-stun” so that it rhymes with “crustacean.”

I never would have thought of electrocution as a means of killing a lobster, because earlier this year, I read a pair of papers by Robert Elwood and Miriam Appel relating to electricity and crustaceans. They were studying hermit crabs rather than lobsters, but most decapod crustaceans have very similar nervous systems and broadly respond to the same kinds of stimuli.

These two papers from these authors are a matched pair. Indeed, the two should have been combined into one paper. Each is very slight, with one experiment that is a variation of the other. In both, they implanted wires into the shells hermit crabs live in, so they could deliver small electric shocks to the hermit crab’s abdomen. In one (Appel and Elwood), they varied the intensity of the electrical stimulus. In the other (Elwood and Appel), they kept the intensity of the electrical stimulus the same, but gave the animals options for new shells to enter should they leave the shells they had been shocked in.

Hermit crabs are unarmored and do not like being outside of their shells. In both studies, they found the electric shock significantly changed the behaviour of the hermit crabs. The crabs left the shells they normally inhabit, and the authors saw some strange behaviours, including some aggressive behaviour directed at the shell. In other words, after getting a shock form the shell, some crabs started treating its shell like an enemy.

Elwood and Appel argue that their results show evidence for electrical shock eliciting pain responses in the hermit crabs. In the context of cooking lobsters, there is more experimental evidence supporting the idea that electric shock is noxious to crustaceans than evidence that high temperatures are noxious.

Nevertheless, there may still be an advantage to the new method in the speed. The Daily Mail article claims that:

The machine can knock a large crustacean unconscious in less than 0.3 seconds and kill it in five to ten. Crabs take four to five minutes to die in boiling water, while lobsters take three minutes.

I can’t help but think of the guillotine, which also had the goal of a quick, humane death. The actual practice of using the guillotine was, I understand, not always so tidy, and I wonder about how consistently the machine will accomplish its task.

The article claims in passing that this device this may improve the taste. I can think of no particular reason that should be, but the flavour issue is something I will leave for others to decide. But I do find it sad that a question that is so often asked generates strong opinions more than well designed experiments.


Appel, M., & Elwood, R. (2009). Motivational trade-offs and potential pain experience in hermit crabs Applied Animal Behaviour Science, 119 (1-2), 120-124 DOI: 10.1016/j.applanim.2009.03.013

Elwood, R., & Appel, M. (2009). Pain experience in hermit crabs? Animal Behaviour, 77 (5), 1243-1246 DOI: 10.1016/j.anbehav.2009.01.028

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