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Nociception can be directly tested for, but there is no objective way to test for the pyschological experience of pain. For centuries doctors “knew” that dogs and cats can’t feel pain. I know that crustaceans can’t. You know fish can’t. But we might be wrong. Fish and lobsters do not have the same pain receptors or circuitry that we do, but whether that means no pain, different pain, or convergent pain evolution. Who’s to say? It really is a question of faith.
That said, years of working with decapods taught me that they do not feel pain, but can recognize and remember people and know who treats them well and they can be fun pets.
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I will have to track down the studies I read. They related it back to whether the behavior that caused harm was repeated voluntarily. Does a well-fed fish repeat harmful feeding behavior? That kind of thing.
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For myself, the first time I saw a crawfish contentedly eating its own tail was when I decided that they don’t feel anything like what we call pain. Ultimately it’s a behaviorist question, though, you look at self-harming behavior and ask would an animal that feels pain ever do that. But people are known to voluntarily engage in painful behavior, so that only gets you so far
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True that.
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A crayfish saved the Swedes from Prohibition
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Did you watch the video? The lobster seemed pretty happy to me (science has shown that their nervous systems can produce serotonin so clearly they have some capacity for pleasure) and appeared to be thriving. Certainly a far cry from how it looked when it was first brought home - starved and with atrophied claws.
It’s certainly not a cuddly ‘pet’ but that doesn’t mean that it can’t be a mutually beneficial relationship - the caretaker has something interesting and low maintenance to care for, and the lobster doesn’t end up on a dinner plate. Seems like a win-win.
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Self-harm seems like a pretty bad criterion…childbirth is often extremely painful and damaging but that doesn’t stop humans from doing it. A recent review argues that the evidence is pretty compelling that fish can feel pain, although still debated.
To be honest, to me this seems like one of those things that would be obvious if it weren’t for people wanting it to not be true. I mean, what else was there to make people guess that fish might not feel pain in the first place? I also found a historical review and it looks like, surprise surprise, the whole controversy has been more about prejudices than evidence to begin with. 
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I think that the usual question(which runs the risk of attracting qualia zombies if poked wrong) revolves around the difference between exhibiting a stimulus response of some sort and experiencing suffering as a state.
Even (relatively) simple mechanical systems can be thought of as exhibiting aversive/protective responses: a device with a torque limiter may disengage from load partially or fully if it is being stressed to avoid damage. We don’t typically suspect suffering(though the ‘scream’ of certain metals being pushed past their failure point is somewhat haunting). Somewhat more sophisticated electric and electronic motor control systems that use back-emf to detect stall conditions are even exhibiting a sort of reflex(since back-emf is a property of a motor being pushed toward stall, not just a separate supervisory system using grey codes or hall effect sensors tacked on, though there may be one of those as well); suffering also not suspected.
At the other extreme, humans are handy because they can(and many are downright eager to) be unreliable narrators of their subjective experiences; and it’s easy enough to find people who are experiencing intense subjective suffering even in the absence of physical pain(eg. people in normal health who have had a loved one die recently).
The big fascinating question is the stuff in the middle; where you can’t just consult the design documents; but you also can’t just ask; and we (unhelpfully) don’t have what you’d call a solid idea of how ‘subjective experience’ actually works, even in places where we strongly believe it to exist; so we don’t exactly know what we are looking for.
There are absolutely aversive stimulus responses down to single-celled organisms; and more complex organisms have more complex ones(and sometimes deeply uncomfortable neural correlates to what one sees in pained humans); but the question remains of what the minimum implementation size for experiencing suffering rather than just autonomic twitching is.
My guess is that it’s smaller than we’d like; and that things that aren’t mammals we find cute get underscored (eg. the idea that schooling fish must obviously lack any sort of social complexity, because their cold, alien, piscid eyes are all weird; but pack hunters are clearly social peers because wolves are just nature doggos and adorable); but when you can get even things like culture-grown muscle tissue to twitch when you hit them with an aversive stimulus not all uncomfortable-looking movement can be suspected to imply suffering.
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I certainly don’t doubt the power of an evolved heuristic hitting a corner case(I’ve always found insects that use optic flow measurements for altitude adjustment freaking out and losing control over certain types of uniform surfaces to be a fascinating one); but I can’t help but think of the racks full of dieting and ‘lifestyle’ magazines (from the Before Times, when retail shopping was a thing) whose entire readership pretty much consisted of people who were being made profoundly unhappy by their implementation of eating and/or spawning.
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Thank you; quite thought provoking.
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Agree the lobster looks a lot healthier and happier
Serotonin is used for lots of things other than pleasure. In lobsters its used to modulate motor circuits, and its used hormonally to regulate aggression and social dominance, and it might also be used in pleasure sensation (harder to test for than change in muscle activity). Neurotransmitters have all been repurposed many times over through evolution and the common ones are ubiquitous in animals
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Yes. There’s a reason I didn’t choose spawning as my example. It’s such a strong biological imperative in some fish that it overrides immediate survival.
I would argue the bias goes both ways. Just as there are folks who look for any scientific rationale to continue their current practice (guilty, myself), there are also people who project the human experience of pain and trauma on other species. As long as we recognize those biases, I think we can have a productive discussion of the science and I would definitely be open to changing my mind if there is compelling evidence.
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Thanks - you provided a much more facts-based take than mine. Maybe rather than “pleasure” a better word would have been “reward”.
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I don’t doubt it, and indeed that is what the same history shows. Though for the record I know you know that angling causes harm to fish in some form or another, and practice ways to minimize that when you can, which I think is admirable. But the reason the question seems like it must have been such obviously motivated reasoning in the first place is because it goes against the main thing we know in biology, which is that living things developed on a continuum of small changes.
I feel comfortable saying fish don’t suffer as profoundly as apes or elephants, with their long memories and complex emotional states, allowing pain to bubble into dread and grief and all sorts of psychological trauma. My naive assumption would be that those feel pain in a more meaningful and less alien way than say rodents, and in turn than lizards, than fish, than crustaceans or snails, than worms, than clams or anemones. What I don’t understand is why anybody would look at all those animals and conclude their must be a sharp line somewhere with pain on one side and not on the other. I personally don’t see anything else in their behavior that suggests things like that.
Something I find very charming is Darwin’s description of the mental qualities of earthworms:
There is little to be said on this head. We have seen that worms are timid. It may be doubted whether they suffer as much pain when injured, as they seem to express by their contortions. Judging by their eagerness for certain kinds of food, they must enjoy the pleasure of eating. Their sexual passion is strong enough to overcome for a time their dread of light. They perhaps have a trace of social feeling, for they are not disturbed by crawling over each other’s bodies, and they sometimes lie in contact.To be sure there is some projection in this even if things like their apparent torture are not taken at face value. But to me it's far more sensible than debates like this. I doubt Darwin would have advocated that it's unethical to use worms in fishing, but he knows he's looking at our relatives many eons removed. Maybe if we stopped trying to figure out where animals switched from Newtonian machines to Cartesian spirits we wouldn't be so surprised every time evidence turns up one of them is a little more like us than we guessed.
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I agree. I would be very skeptical if someone did attempt to describe a hard line between organisms that feel pain and those that don’t. I have a big enough problem with human-defined taxonomies determining policy (esp. w.r.t. animal-plant designations) that I would not easily accept such a line.
As I continue to grow and learn, there are often times when I’m fishing when I find myself not actually fishing, but rather just being in the environment of fish and observing them. I move more and more away from seeking capture and more towards just interaction.
On one hand, I’ve caught the same trout twice within 5 minutes on the same fly. Clearly, being caught and released was insufficient stimulus to change short-term behavior. On the other hand, I’ve observed not just intraspecies cooperation but interspecies cooperation between fish - specifically, largemouth bass hunting collaboratively with carp - that indicate a higher complexity than most people give them credit for.
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Does that qualify as a crawdad joke?
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Oysters apparently don’t, or likely don’t.
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Followed by The Tick chewing up starfish and spitting them out to feed them.
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