Can (some) crustaceans feel pain?

As a follow-up to my previous post on speciesism, it is of interest that a soon to be published paper in Animal Behaviour provides tentative evidence of pain in decapod crustaceans (which includes lobsters, crayfishes [crawfishes or crawdads], crabs, shrimps, and prawns). I came across this through a news report in New Scientist that showed up in my RSS feeds and it seemed worthy of mentioning.

Both the New Scientist report and the primary article are behind subscription walls, but here is the abstract of the paper:

Nociception or pain in a decapod crustacean?

Stuart Barr, Peter R. Laming, Jaimie T.A. Dick, and Robert W. Elwood
Animal Behaviour, in press

Nociception is the ability to perceive a noxious stimulus and react in a reflexive manner and occurs across a wide range of taxa. However, the ability to experience the associated aversive sensation and feeling, known as pain, is not widely accepted to occur in nonvertebrates. We examined the responses of a decapod crustacean, the prawn, Palaemon elegans, to different noxious stimuli applied to one antenna to assess reflex responses (nociception) and longer-term, specifically directed behavioural responses that might indicate pain. We also examined the effects of benzocaine, a local anaesthetic, on these responses. Noxious stimuli elicited an immediate reflex tail flick response, followed by two prolonged activities, grooming of the antenna and rubbing of the antenna against the side of the tank, with both activities directed specifically at the treated antenna. These responses were inhibited by benzocaine; however, benzocaine did not alter general swimming activity and thus the decline in grooming and rubbing is not due to general anaesthesia. Mechanical stimulation by pinching also resulted in prolonged rubbing, but this was not inhibited by benzocaine. These results indicate an awareness of the location of the noxious stimuli, and the prolonged complex responses indicate a central involvement in their organization. The inhibition by a local anaesthetic is similar to observations on vertebrates and is consistent with the idea that these crustaceans can experience pain.

Let me say this before the comments begin: I don’t think anyone is claiming that prawns can experience the same kind of pain, including emotional pain and anticipation of pain, that humans can. The point is simply that we cannot automatically dismiss all reactions to noxious stimuli in invertebrates as reflexive nociception. There could be something more to it.

6 thoughts on “Can (some) crustaceans feel pain?

  1. I seriously don’t understand the argument the authors are making — just because the animal can tell where the stimulus is coming from in no way denies the reflexive nature of the action or supports the idea that it is feeling “pain”. Many existing electronic devices can report where a fault occurs and some can even try to treat the fault; according to such an argument this means that these devices can feel pain too.

  2. It’s a difficult question, that’s for sure. It’s similarly difficult when discussing human fetuses or infants, as you may know from other controversies. I think that’s why solipsism or assumptions about universality dominate such discussions, typically determined by what people already believe without evidence either way.

  3. It’s a difficult question indeed, and I’m not saying that I know that crustaceans *don’t* feel pain. However, I really don’t see what relevance this study has to the question, nor what relevance “solipsism” has to the problem. I don’t think either of us doubt that a physical universe exists outside our minds and crustaceans physically exist in it.

  4. As used in less silly forms of philosophy, “solipsism” means that one cannot know the state of the mind of any other species and usually is followed by assumptions that they are not capable of human-like thought, feeling, or whatever.

    For example:

    Ridge, M. (2001). Taking solipsism seriously: nonhuman animals and meta-cognitive theories of consciousness. Philosophical Studies 103: 315-340.

  5. Ah. It’s a case of “framing”. A reasonable position has been made to seem unreasonable by associating it with the name of a philosophical position commonly understood to be silly.

  6. I don’t know — maybe. But I *hope* philosophers have rejected the silly version enough to not find the alternate view little more than framing. And it doesn’t really matter to me personally — call it whatever you like, perhaps “unknowablemindism”. Makes no difference to what the argument is.

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