Crabs and other crustaceans not only feel pain, new research has found, but they remember it—and use the experience to try to avoid future shock. For the study, published in Animal Behavior, researchers Robert Elwood and Mirjam Appel looked at how hermit crabs reacted to small electric shocks. Using wires, they delivered the shocks to the abdomens of the hermits who take shelter inside other mollusks’ abandoned shells, and found the crabs would scamper out of the shells after being shocked, “indicating that the experience is unpleasant for them,” the scientists concluded; unshocked crabs stayed put [LiveScience]. The researchers say their study proves that this response is not just a reflex, but that central neuronal processing takes place [CNN].
The role of pain, according to Elwood, is to allow an individual to be “aware of the potential tissue damage” while experiencing “a huge negative emotion or motivation that it learns to avoid that situation in the future” [Discovery News]. Prior research had shown that crabs can detect and withdraw from harmful stimuli, but it was not certain whether that was a simple reflex mechanism, disassociated from the feeling humans recognize as pain.
In one part of the study, the researchers delivered shocks that were just below the threshold that causes a hermit crab to instantly scamper out of its shell, and watched what happened when a new shell was then offered. Crabs that had been shocked but had remained in their shell appeared to remember the experience of the shock because they quickly moved towards the new shell, investigated it briefly and were more likely to change to the new shell compared to those that had not been shocked [CNN]. The observations illustrate a tendency by the crustaceans to weigh trade-offs between meeting certain needs, in this case the quality of shell, and avoiding pain—similar to the way humans make some decisions.
Since crustaceans don’t have a brain structure called the neocortex that processes pain and stress in humans, some researchers had theorized that creatures like crabs and lobsters can’t feel pain. But in another paper not yet published, Elwood and his colleagues argue that crustaceans possess “a suitable central nervous system and receptors” [Discovery News]. Elwood notes that these animals lack protections, but says that if any legislation were to pass regarding treatment of crustaceans, it would be more likely applied to animals only in scientific research, rather than to those raised for food. But the study, he added, highlighted the need to investigate how crustaceans used in food industries are treated, saying that a “potentially very large problem” was being ignored [BBC].
Related Content:
80beats: Fiddler Crabs Meticulously Measure Their Strides to Find Their Way
80beats: Iron-Dumping Experiment Is a Bust: It Feeds Crustaceans, Doesn’t Trap Carbon
Image: Flickr / vonlohmann
March 28th, 2009 at 2:40 am
All animals feel pain, I think. Pain = destruction of self. Ability to sense destruction of self and avoid it is one of those most-necessary traits of life as we know it. It’s one of the few things all animals that have lived this long have in common – the ability to try to avoid harm to the organism. It may be more or less refined in other organisms, but it’s there.
March 28th, 2009 at 11:31 am
I think the problem though is what “pain” really is. In humans, it is a combination of a physical stimulus, conscious & unconscious emotional response. Based on our ability to reflect on, and contextualize, the experience, different people can have very different experiences to the same physical pain stimulus. Animals may not have consciousness, but they certainly have an unconscious, and one wonders what role this plays in an emotional response.
March 28th, 2009 at 1:01 pm
¿what do you think about boiuled lobsters???????????????????????????
March 28th, 2009 at 7:25 pm
It is common sense. All organisms that are ambulatory have tactile senses of which pain is one of the more intense one. Natural self-preservation.
If an organism has a brain to decipher electrical impulses and a nervous system to carry the said impulses to the brain, we should safely assume they feel pain.
Let us now wait for the accursed industry to come up with a whole lot of justifications to convince us otherwise.
This is not a life or death situation. This is one more way we pander to our lower base animal instincts. Find a more humane way of consuming these live, feeling and fearful of God’s creatures if you cannot completely give them up.
March 29th, 2009 at 4:11 pm
I would not be able to eat a boiled lobster again because I think that method of killing is so inhumane.
March 30th, 2009 at 6:18 am
they die pretty quickly going in head first, only sickos boil them tail first…
March 30th, 2009 at 9:33 am
@thom: We know that the perception of time is not absolute even for an individual, it depends on many factors. In case of another species the difference is, I suppose, much greater. What is a mere moment for us might be a long time for a small animal.
March 30th, 2009 at 2:04 pm
um, did somebody say: “consider the lobster”!!??
gourmet.com/magazine/2000s/2004/08/consider_the_lobster
April 29th, 2009 at 8:37 am
Instead of having a pain reflex, lobsters and crabs should just make themselves less tasty. Then, there won’t be a problem.
September 14th, 2009 at 3:10 pm
The way we kill lobsters is vile. I can’t eat any shellfish because of the methods we use to kill them…
September 16th, 2009 at 8:43 pm
First I want to comment on the subject of pain. We humans have a complex neuro system. Pain to us is more descriptive in our brains because we have more receptors. (Kind of like a high-res monitor is very sharp/clear.) Lower animals have less (and would be like the old VGA monitors, or less, in this comparison). So let’s say you get stabbed in a mugging … very painful!!! Now, let’s say you spear a fish… does the fish feel it? Heck, yeah! BUT, the pain WON’T be as intense as we would imagine it (like in the mugging mentioned above). It would be more like a “sharp thud” to the fish. God put fewer neuro receptors in lower animals for a REASON.
This brings me to my second comment. We’re talking predator vs. prey here. When predators like, say, lions or raptors go after prey, though they are efficient hunters, they may not always hit their mark on the first try. This means that, a lot of the time, the prey animal is maimed before it it brought-down and dispatched. Now, have you ever noticed that predators have their eyes more toward the front of their heads, and that prey animals’ eyes are to the sides? (This is for a reason, folks.) With that in mind, as humans, where are our eyes? That’s right, we’re PREDATORS! Now, stop whining and eat your shellfish! Oh, and if you are a vegan, you’re still killing plants. You must kill (or eat something that has been killed) in order to survive. Period.
…and I’m not saying to torture the lobster – I’m saying that the methods used to dispatch and prepare these shellfish for our consumption is absolutely within reason. Peace-out!