The Misunderstood Crustacean: Study Suggests They Do Feel Pain

By Rachel Cernansky | March 27, 2009 3:37 pm

crab.jpgCrabs 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].

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Image: Flickr / vonlohmann

CATEGORIZED UNDER: Environment, Living World
MORE ABOUT: crustaceans, ocean, senses
  • Nick

    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.

  • Eli

    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.

  • tu anciana abuela

    ¿what do you think about boiuled lobsters???????????????????????????

  • Prem Das

    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.

  • Eileen

    I would not be able to eat a boiled lobster again because I think that method of killing is so inhumane.

  • thom

    they die pretty quickly going in head first, only sickos boil them tail first…

  • hat_eater

    @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.

  • JR Minkel

    um, did somebody say: “consider the lobster”!!??

  • Jim Gwonkley

    Instead of having a pain reflex, lobsters and crabs should just make themselves less tasty. Then, there won’t be a problem.

  • CA

    The way we kill lobsters is vile. I can’t eat any shellfish because of the methods we use to kill them…

  • redtailhawker

    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!

  • SBuckley91

    @redtailhawker Who the hell are we to say how they feel? What, were you a “lower animal” at one point in your life? Did you EVER feel the pain they felt? I personally know I am not sure what they feel. I have no clue. However, I would rather say that they feel pain and avoid torturing the poor creature then saying they feel little or none and putting it through excruciating pain.

    Yes. Predators may miss. But MISS means it was an accident. I don’t think that bringing a pot of water to 325 degrees placing the Lobster in, seasoning the water and closing the lid counts as an accident. I don’t even like slicing them in half. There are tons of stories about humans heads getting chopped off in a guillotine and still reacting to stimuli.

  • Brent B

    @Redtailhawker – Aye, true but we have BOTH while they only have ONE. We as humans can compare the two types of pain, while the “lower animal” only has the one. You have NO basis for assuming how intense the pain is for these creatures, or whether its any less (or greater for that matter) than the pain we experience. The fact that they only have these “limited” pain receptors might make the pain all the greater? It could intensify the emotional response..etc any number of factors could make the pain equal or greater than the pain we experience.

    I’m not saying it IS one way or the other, but I concede that I really don’t know as I have never been a lobster.

  • Brent B

    Also, so God put fewer neuro receptors in their brains so that pain wouldn’t be so bad when we brutally killed them for food?

    What an asshole.

  • Sherp

    I’m surprised at how much god is being brought up… “lower animal” or not, it just seems like common sense to assume that organisms feel pain to some degree for the purpose of self preservation. As a human that’s not prepared to give up my omnivorous, seafood-loving ways, I think that with regards to the food industry it’s important to minimise the pain of death for these animals as much as possible. A large, sharp knife quickly brought down through the head to destroy the brain tissue prior to boiling sounds like it would do the trick to me.

  • david

    The complex nervous system was probably among the very last to develop among animals in evolutionary history. This is clear when investigating the development of animal foetuses which is sort of a time capsule of evolutionary development. In other words many primitive organisms protected themselves and responded against damaging stimuli without the necessity of “pain”.

    Lobsters may have a very primitive or basic nervous system, but it’s clear because of their brain structure that scientists can deduce that they don’t have complex brain process that show self-awareness . So the notion of “suffering” isn’t really an issue. Self-awareness is a requirement to comprehend neurological signals as something “bad happening to me” .

  • anthony

    If you want to kill lobsters humanely just slice through their head with a knife before cooking them. No brain no pain!


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