The ethical case for eating oysters and mussels

It was five years ago this month that I became vegan, or…well, ostrovegan. In this blog I oystersofficially come out of the closet, err, shell.  I am almost sure that cultivated mussels and oysters are ethical to eat. I argue eating these animals is completely consistent with the spirit if not the letter of ethical veganism and the tenet of causing less harm with our consumer choices 1. This blog is on bivalve sentience/ability to suffer; for further arguments, including nutrition arguments, see my second blog.

Are mussels and oysters sentient?

Dividing organisms up into types, or cladistics, is tricky business. Nature did not develop in a way that fits neatly into categories. Dividing up organisms on the basis of sentience, or the ability to suffer, may be even trickier. So, is there any evidence that mussels and oysters don’t suffer?

Argument 1- Oysters and Mussels are not motile

Let me start with a perspective derived from evolutionary theory about how organisms are designed. The function of pain is to help an organism avoid stimuli that may cause them bodily harm. Organisms that are sessile, or unable to move, cannot escape pain and thus there really isn’t any adaptive reason for them to feel pain. Sessile bivalves can open and close their shells but this is as simple an action as plants who close in the presence of noxious stimuli and for a variety of reasons I won’t go into here, plants don’t feel pain. The definition of vegan typically includes not consuming anything of animal origin. And, as animals are most often motile and thus have an adaptive reason to feel pain, this makes sense.

But, mussels and oysters are closely related to other species (e.g. scallops2, squid) who are motile and thus, by my logic, can feel pain, is it possible that they have some leftover capacity to suffer from a common ancestor?3

This is very unlikely because pain is biologically expensive4 In order to feel pain an organism must have to have a sensory system capable of differentiating ‘good’ or adaptive stimuli from ‘bad’ or harmful stimuli. On top of this, the experience of pain is often damaging in and of itself. Finally, in order to facilitate moving away from pain an organism’s priorities change. For instance, pain reduces hunger and the desire to mate. Given that no system is perfect and there is always some rate of misfiring, a sessile organism that experiences pain would get all the harm and none of the benefit of moving away from painful stimuli and thus be at a disadvantage.

-Oysters and mussels have a larval stage that is motile (see this and this). During this larval stage the animals react to stimuli and may even hitch a ride on fish to disperse more widely.  Also, freshwater mussels (which are not commonly eaten by humans) are more motile and can move (albeit slowly). During the larval stage there are neurons present however “many of the larval neurons disappear after metamorphosis“. Both of these facts make me less confident in the motility argument but I still think the other arguments below stand on their own. /Addendum

Argument 2- Oysters and mussels have rudimentary nervous systems and do not seem to use endogenous opiates or opiate receptors to inhibit pain

Mussel nervous system

“[The bivalve] nervous system includes two pairs of nerve cords and three pairs of ganglia. There is no obvious cephalization and the nervous system appears quite simple….to our knowledge there are no published descriptions of  behavioral or neurophysiological responses to tissue injury in bivalves (Crook& Walters 2011).


Translation: Bivalves have a very simple nervous system which is not aggregated in anything like a brain. Other invertebrates, like shrimp, show changes in behavior (e.g. grooming their antenna after injury) neurotransmitters or neural firing in response to injury, but previous studies have not shown this kind of response in bivalves.

My conclusion: Bivalves do not have hardware or response consistent with the ability to feel pain. Because they have no brain, or central processing unit for stimuli, there is no ‘there’, there. Just like a disembodied finger, there is no place for sensations to be aggregated into responses or changes in adaptive decision making.5

Many animals have opiate receptors, indicating they are making painkillers and regulating pain within their own nervous system. One way that animal pain is gauged is to administer opiates and see if it influences the behavioral response to pain (e.g.). There is some evidence that bivalves have opioids and opioid receptors but 1) there isn’t good evidence that bivalves have the genes that code for these receptors and 2) it seems that opiates are being used to signal the immune system not to regulate pain. To be honest this is the point on which I am least confident and on which science isn’t yet conclusive.

Argument 3- Eating cultivated oysters and mussels doesn’t doesn’t kill other (sentient) animals at a rate greater than agriculture

Line grown mussels

No food is completely deathless. When you eat plants or grains you are often supporting a  system that kills insects, rodents, and displaces wild animals. Let’s say that you eat shrimps because you doubt that they are sentient. Even if you are on an invertebrate only diet, many species are dredged or netted which involves bycatch, or the deaths of many other organisms after they are harmed by being brought up out of the water and thrown in again. With shrimp, for instance, the rate of bycatch is enormous, sometimes up to 98% of what is caught is discarded, and much of this bycatch is vertebrates. Surely, eating animals that aren’t sentient could not be ethical if it involved significant numbers of deaths for animals that are sentient.

Mussels and oysters, on the other hand are most often farmed in a way that doesn’t involve harm to other sentient beings. From what I can tell from reading in depth about cultivation:

-The only dredging involved in cultivation is collecting spat, or the “seeds” that become mature mussels, however rope cultured mussels don’t generally involve dredging for spat but collecting it on the surface thus not displacing other organisms.

-Oyster and mussel cultivation has been endorsed as good for water quality (e.g. they filter out excess nitrogen) doesn’t involve antibiotics and doesn’t involve killing other animals to feed to them as is the case with farmed fish (e.g. this source is not objective but details many potential environmental benefits from shellfish aquaculture).

-Eating oysters and mussels may involve less other animal death and displacement than eating grains or soy (although I have yet to do a proper calculation on this)

In the next blog I’ve argued that including oysters and mussels as ethically acceptable on a vegan diet undermines naturalistic, nutritional and emotional arguments against veganism thus promoting ethical eating. I’ll also speculate about whether there would be fewer vertebrate eating ex-vegans if ostrovegan was considered an ethically acceptable in a vegan diet. 


1-I’m not the first to argue this. This Slate piece from back in 2010 sketches the argument from sentience and Peter Singer has also been on both sides of this argument earlier endorsing and later renouncing the view that eating sessile bivalves is ethically neutral.

2-I endorse giving motile bivalves like clams and scallops the benefit of the doubt and not eating them. Scallops can swim away from predators and have eyes, which makes them a great deal more cognitively sophisticated.

3-Hat tip to Ian McDonald for pointing out this possibility

4– Brains, often needed in motile organisms, are also biologically expensive:

“The juvenile sea squirt wanders through the sea searching for a suitable rock or hunk of coral to cling to and make its home for life. For this task, it has a rudimentary nervous system. When it finds its spot and takes root, it doesn’t need its brain anymore, so it eats it! It’s rather like getting tenure.” – Daniel C. Dennett

5David Pearce, who disagrees with me and thinks that we should give oysters and mussels the benefit of the doubt (partly because of possible opiate receptors) has conceded this:

“Just as I think it’s possible some of our peripheral ganglia feel phenomenal pain that is inaccessible to the CNS (cf. how one sometimes withdraws one’s hand from a hot stove before one feels the searing pain) it’s possible mussels and oyster ganglia feel something similar. But rights for individal nerve ganglia clearly can’t be high on our list of moral priorities”

281 thoughts on “The ethical case for eating oysters and mussels

  1. A good article. However, I’d say that your points undermine the argument against eating these animals (on grounds of suffering) more than they provide an argument for eating them.

    • Agreed. I intended to include the argument that including oysters and mussels as vegan might encourage people to eat ethically but decided to do this in a followup.

      • I was only interested in eating mussels and oysters purely because they are a fabulous natural source of b12 (over 90 grams of it, in one serving), and I heard rumors that they didn’t feel pain and didn’t have brians. It was elating to read this article! I hope that this catches on with other vegans. 😛

  2. Interesting argument but not sure motility=pain sensation. Doesn’t the logic only apply if source of pain is external?
    Also would be interesting to know if CNS of clams/scallops substantially more complicated than that of mussels/oysters.

    • Thanks K. I’ve been looking into this and it seems that in scallops the ganglia are better connected but I haven’t heard the same of clams. And you’re right, internal pain could be important to regulate homeostasis. Recently I’ve relegated the motility argument as a more minor point with the argument about the lack of neural hardware itself as most important.

    • Who ever wrote that article is a closed-minded “dictionary-vegan” and those are the religious type of vegans who treat veganism as a cult, rather than a flexible ethical/ logical/ environmental approach to go about food choices, entertainment, clothing and daily living.

      If an animal is brainless and cannot interpret pain, then it is ethical to eat it. We shouldn’t base our food choices just on rather a earthling has plant cells or animal cells. What if for all practical purposes a creature was discovered to be made completely out of plant cells, and has a consciousness and santience. According to the logic of a “dictionary-vegan” it’s ethical to eat this creature, simply because it’s a plant. We, as a society, have to stop being so closed-minded and think past labels and dictionary terms, especially since the vegan community is deficient in a few vitimins..

      • Based on your argument Candygurl, it would be permissible to eat humans that are in a vegetative state, those who are brain dead. Why let all those bodies of people in comas go to waste when we can eat their flesh, right? Part of the problem is that there’s too many “flexi-vegans” trying to dilute the original intention and definition of veganism to suit their own desires. If we can avoid eating oysters (and we can) then we should. being vegan is easy. There’s no need to find excuses to not be. Your point about the vegan community being deficient in vitamins might be true in those who eat poorly, but it’s also true for any other person who isn’t vegan who does not ensure they get adequate nutrition.

      • Tim, eating humans in a vegetative/brain dead state is not the same as killing an animal that is born with only 3 ganglia. In addition, there is reasonable doubt and social reasons to not eat a human even if the human appears to lack brain cells.

        People eat plants because they don’t think, feel pain, or want to live. Vegans don’t eat animals because they feel pain, can think, and want to live – this is determined by an anatomical/physiological difference that animals have which allows them to think. If a “vegan” was eating a marine sponge, which has nothing resembling a brain or nervous system, nobody would complain that it was unethical. It is not unreasonable for someone to say “I’m going to be vegan except for mussels, and if someone finds reasonable evidence that they may be able to think or feel pain, then I will stop” then this is nothing like someone saying “I’m gonna be vegan except for cheese/chicken/fish” because there is very strong, irrefutable animals which those products come from suffer and want to live.

        In terms of health, it seems it’d be easier to avoid zinc, iron or B12 deficiencies for someone who is vegan except for oysters/mussels. They are also high in omega fatty acids. I have 2 people close to me who eat mussels/oysters but are otherwise completely vegan – and I respect that. For me, I never liked the taste of mussels/oysters, but I worry about my diet a lot because I don’t always remember to supplement zinc, I have anxiety which makes me often lose my appetite and have been tired lately.

        I think there is a huge problem in the vegan community of victim blaming; people make claims that the vegan diet is the healthiest out there, although our ancestors did not eat this way for the most part, and although it seems it should be fine to get nutrients from plants, it takes a little more effort to ensure you have everything (B12, zinc, iodine, omegas, calcium), and also from experience is pretty inconvenient to have to test for whatever deficiency you may have. I think for this reason especially, it’s absolutely ridiculous for vegans to attack those who are eating mussels/oysters when those vegans cannot prove that the mussels feel pain, think, or can suffer. Nobody would be stupid enough to claim that killing an oyster is the same as killing a chicken or dog.

      • I agree Danielle that killing an oyster is not the same as killing a dog or a chicken, just as killing a human foetus is not the same as killing a human infant. If it can be avoided )and it can be where alternatives are available for nutrition), then I’d suggest it’s best to avoid killing and eating oysters. My main concern is with people calling them selves vegan whilst they’re consuming oysters, because by definition they aren’t vegan, and preceeding the word vegan with terms like “ostro” doesn’t make them vegan but something else. I don’t think they should be using the word vegan at all to describe who they are and what they eat.

      • Complaining about ostroveganism is similar than Unilever trying to sue Hampton Creek for having “mayo” that does not contain eggs. What you are arguing for is a dictionary, religious/dogmatic-type definition of veganism, rather than looking at the ethics of each case.

        When someone proves to me that oysters can think or feel, then I will be opposed to the eating of oysters and mussels. Although this is hardly more likely than people finding out that plants feel pain. Until then, I can understand that my friends are going to eat them, because they are a good source of zinc, omegas, iron and B12 (moreso than vegan sources), and they have not been shown to feel pain. I’m not complaining about people giving oysters and mussels the benefit of the (small amount of) doubt, I’m just saying there is a culture in veganism of victim blaming and pretending that vegan diets are the healthiest, when it actually takes more work to ensure you’re getting the right nutrients. Yes, I do think fortification would happen if there were a higher proportion of vegans in society, but I also don’t think there’s anything wrong with eating an animal which you cannot prove feels pain or thinks.

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  5. Great post! As a vegan, I have long wondered about this myself, sometimes even considering eating insects or other invertabrates like oysters. I never even tried it though, since it seems “icky”, and they do feel pain to some degree(and environmental and health concerns). Your line of reasoning9which doesn’t mean it’s wrong) resembles arguments I’ve seen in favor of “pescatarianism” – basically almost vegetarians who will eat fish, but no other vertebrates or animal flesh. I think “fish”(such a broad category) feel a lot more pain than oysters.

    When it comes to oysters and mussels, even if they feel no pain at all, there still is the issue of toxins accumulating in shell-“fish”, like mercury and lead. This is a serious health concern, in my opinion. I will explore this issue further, since I’ve long been into sentience and cladistics.

    • Since bivalves are at the bottom of the food chain accumulation of toxins would not be a huge concern. Moreover, accumulation of toxins (e.g. heavy metals in rice) in plants is a well-known phenomenon.

    • Actually animals at the top of the food chain are likely to accumulate toxins more generally but filter and bottom feeders have this problem as well. This should be the next thing I look into carefully.

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  7. Plants DO feel pain…plants respond exactly how one should when in pain…although the plant can not run away like most animals can. When we bleed we are feeling pain it is thus logical to accept that when a plant is oozing sap or releasing toxic chemicals ‘bleeding’ it is in some sort of state of pain. Its not a question of pain ratio it is the question do plants feel pain…well, yes of course they do. Plants can and do respond to other stimulis such as suffering from disease and neglect and respond to healing treatments such as energy healing using bush essences and bach flower essences and studies have been done where heavy metal music made plants sick and depressed but when placed infront of classical and soothing music responded in healing alive and healthy. I’m not about to say that eating plants vegan is cruel because that’s is just stupid, and yet there are people out there that do support that rubbish because they can not accept people being compassionate and aware of ethical and kindness towards animals:veganism and vegetarian. All I’m saying here is plants DO feel pain and are AWARE of pain…you just can not hear them…like the fools that believe fishing and ripping hooks out of marine life dont feel pain…they can and do…more so infact their mouths and lips are EXTREMELY sensitive to pain and for a person to yahoo and laugh at how they’ve caught a fish on line is just as cruel and sickening as clubbing seals…people ALWAYS try to recify their errors with bullshit justification!

    • The seal clubbing simile is ridiculous so is the blood to sap one. If a living thing has a brain only then can it feel pain would be a logical assumption. Even worms have a sort of primitive brain.

    • Eve, it might help you to understand why plants (probably) cannot feel pain if you think of them as complex machines (much like us animals). Unlike animals, though, plants just aren’t ‘wired’ to feel pain. They lack neurons etc… The physical responses you mention are reflexes to stimuli programmed into the plant/machine to increase its chance of survival. Eg.plantgravitate to sunlight, ooze sap t fill holes, may respond poorly to heavy vibrations

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    • Animals, for the most part, are multicellular, moving organisms with sensory systems guiding their behavior and enabling the possibility of pain. Animals like sessile bivalves and sea sponges were easier to put into the “Animal” kingdom than any of the other kingdoms and sessile bivalves are closely related to mobile bivalves. I am pretty sure that nobody thought this classification was going to have any ethical implications when they made it.

    • This is because they are eukaryotic, multicellular, and heterotrophic (they can’t produce their own food). Also, they have cellular membranes as opposed to cell walls.
      Fungi are eukaryotic, multicellular, and heterotrophic, but their outer membrane is a cell wall made out of chitin.

      Source: I’m a microbiologist 😀

  9. Great article; thank you! I emailed a neuroscience prof about whether oysters feel pain and are conscious and he replied:

    Oysters, like other invertebrates, have very simple nervous systems and neural connections, containing only a few thousand nerve cells (as opposed to the billions that mammals/vertebrates contain). Also, oysters do not contain the pain signaling pathways or the neurotransmitters used in those pain pathways that vertebrates have. As such, oysters are not considered to have consciousness or to perceive pain.
    (Did not ask his permission to quote him so will not include his name, but I presume this is common knowledge among experts)

    I am vegan and have been for years but I think I will start eating oysters soon. I really appreciate your article on a subject where there are few sources of info available to the non-expert.
    My knowledge of biology is minimal, but if a comparison of plants and oysters was made by an expert I think it would be helpful 🙂 I understand that plants react to their environment and can adapt. I have wondered for a while how that compares to the ‘behaviour’/reactions of oysters, if there are any. If it turned out that they are similar in function and structure complexity (even if they are different in biochemical construct) what reason could there possibly be to eat plants and not oysters? If it turned out that oysters are more complex then this would not be helpful 🙂

    • Very interesting, thank you! I’m heartened that other experts agree with me, broadly. Also, I am staking out a bivalve expert to shore up (or disagree with) my clams, I mean, claims 🙂

    • Strangely, this professor’s response makes me less sure, not more, as he so casually lumped all invertebrates together. Cephalopods like the octopus have extremely complex nervous systems and are quite intelligent. They are also very alien and developed their nervous system in almost complete isolation compared to us. (We are more closely related to sea stars than we are cephalopods!)

      The fact he doesn’t differentiate oysters from other invertebrates shows he really didn’t think this through or apply much expertise.

  10. i just made a delicious salad with mussels and was wondering if that would be the last time I ate them since I pretty much became vegan a while ago… After reading this blog I think I’m fine eating mussels (I studied Biology and I just finished my MSc in animal behaviour and welfare, so I really gave it a thought tho!) Thanks for posting!!!

  11. Thanks for your blog. Critical thinking in veganism is most welcome. You mention the absence of studies showing that oysters respond physically to pain stimuli. Being an ‘ostrovegan’ myself, not long ago I squeezed lemon juice onto freshly shucked oysters and was hirrified to see them flinch. I figure it would take a network of neurons to allow such a signiicantt, while-of-body movement. It looked like they were reducing their surface area to decrease the permeability or exposure ofthe the acid. In the wake of your info on nerves and opiate receptors

  12. Thanks for an interesting blog. I didn’t know these molluscs have nerve ganglia & opiate receptors. Could explain how/why live (freshly shucked) oysters flinch and contract their entire bodies when squirted with lemon juice. This blog is making me rethink my own ostroveganism!

    • Interesting point. I wonder if that is just an effect of osmosis, water traveling out of cells because the chemical gradient has changed. Another possibility is that there is a mechanism to wash away irritants from inside the shell. However, neither one of these moves me to change my view on their sentience.

  13. Excellent research for this article! As I’ve mentioned before, I disagree with the conclusion because I think the chance of bivalves suffering is at least ~5% considering how little we understand sentience, and you have to eat more than 20 bivalves to substitute for a chicken or cow.

    A friend pointed me to an article ( on mussels showing “behavioural plasticity with respect to predation risk.” You mentioned that “Sessile bivalves can open and close their shells,” so presumably you don’t find this especially relevant. However, I think the idea is that because the behavior is graded, it demonstrates a tradeoff calculation rather than a binary open/shut decision. Even so, one could certainly argue that graded tradeoffs can be done with simple neural arithmetic and needn’t require sentience. I don’t know if mussels ever learn to close their shells more based on bad experiences or if this is purely hard-wired.

    I’m no longer convinced that plants are not sentient. On this question I would agree with David Pearce that, even if so, plant sentience is not high on the ethical-priority list, but would care to a nonzero degree about hurting plants (

    My guess is that crop cultivation is more likely good than bad for wild animals (, though concerns about global stability may push us toward not supporting it in certain cases, such as where it’s likely to exacerbate water conflicts.

    • Brian! thank you. I admire how you evolve on these ideas. I have yet to fully research how cultivating mussels and oysters might influence other animal species. It’s unclear how many other animals are brought up and killed on the rafts or ropes. Also unclear is the calculation of the influence on suffering of their filtration of the water.

      • 🙂 The problem with changing my mind is that I have to update my website in several places, but so it goes.

        Over the weekend I was thinking more about how much learning should be considered essential for caring about organisms, and I wrote this: So I think I definitely do care about oysters and mussels at least a little bit, but the fact that similarly simple algorithms might be seen in many other places drives an intuition that they do count less per animal than, say, chickens. The big question is “How much less?” and there I’m not sure.

    • Brian, I read the manuscript and my comment is that this type of learning can be isolated to a single neuron. In fact, the GSW reflex model that led to Eric Kandel’s Nobel prize can be replicated by repetitive puffing of 5HT onto a single neuron. Would you consider this individual neuron be “sentient”?

      Many simple behavioral responses (even true associative learning) are just second messenger cascades (e.g. nothing more than transient chemical reactions). As an ex-neuroscientist and current molecular biologist I am as certain about the lack of sensory awareness in oysters as I am about DNA encoding genetic information. IMO, if oysters are in any way sentient, they are sentient via a mechanism that is completely unknown.

      • Hi unethical_vegan 🙂

        Are you suggesting that the tradeoff regarding how much to feed and how much to avoid predators can be done by a single neuron? My guess is that arithmetic like this would need several neurons (some excitatory, some inhibitory?).

        Regardless, I think a single neuron can potentially be marginally sentient. More complex groups of neurons are more sentient. If you want to read more on where I’m coming from, see

        “Many simple behavioral responses (even true associative learning) are just second messenger cascades (e.g. nothing more than transient chemical reactions)”
        All of neuroscience is built from chemical (and electrical) reactions. The difference is one of complexity, of degree rather than kind.

      • Brian, I’ve read through your site on several occasions. (I’m a prioritarian so we would disagree alot.)

        “My guess is that arithmetic like this would need several neurons (some excitatory, some inhibitory?).”

        Classical conditioning of the GSW reflex requires two neurons but the behavior itself can be “encoded” by a single neuron. This form of learning replicates the same type of adaptive response observed for fresh water mussles.

        And here is an example of classical conditioning of a single macrophage:

        “I think a single neuron can potentially be marginally sentient.”

        I think you are redefining sentience to encompass autonomic responses mediated by *hard-wired* molecular switches. The standard definition of sentience requires perception or awareness of sensory input, not just a stimulus response. All documented cases of awareness of pain/sensory input involve extremely large numbers of highly interconnected neurons. Since oysters lack sensory afferents that target interconnected ganglia I believe they unambiguously lack the machinery for sensory perception.

    • if you care about potential plant pain, the idea is not to eat animals, as they eat FAR more plants to create one pound of meat than we would consume in vegetable pounds. Besides the fact that you are also killing the animal. That is a no brainer. although many fruitarians solve possible plant pain by only consuming plant parts which are meant to be consumed and do not kill the entire plant

  14. I’m sorry my text was cut in the middle.
    I was trying to say that if we are to eat any food that is not veg, and if we need nutrients from an animal source and supplements are not sufficient long term, then i think that cultivated mussles are the best choice. So this is what I have been doing for the past 2 months. Before that I was vegetarian for 17 years, choosing vegetarianism as a young girl. However I cannot stand the way cows and chickens are being treated. I am glad to have found some more information about this way of eating.

    • Surely if ‘we cannot be absolutely sure they are not sentient’ (and presumably feel pain) we cannot be defined as vegan? Also, synthetic B12 is a viable form of the nutrient.

      • Dawkins has said that on a 7 point scale of atheism he would put himself at a 6, that is, there is very low probability of their being a god, just short of zero. I feel the same way about the suffering of oysters and mussels. Certainly we cannot be 100% sure that all plants do not feel pain either. We all work in probabilities with different thresholds for deciding we endorse a belief or a behavior.

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  16. I have been eating raw oysters about once a week since I moved to North Carolina. Other than that, my diet is vegan. I felt weird at first, because they are still alive. Whenever I feel run down, I eat some oysters. From what I know, there aren’t very good B12 substitutes. I was always told to use nutritional yeast, but I hear from a lecture, it’s not a good source.

    For the most part, I don’t feel bad eating the oysters. Sometimes I do. They are living, but so are plants. I think it’s just part of living. The goal for me is to cause the least harm.

    • Hi Just Me. Thanks for sharing. Do you think it would be worth at least killing the oysters quickly before eating them? Remember, the probability they can experience pain is greater than 0%, so it seems prudent to take simple steps to prevent potentially significant suffering by being chewed up or digested alive. For instance, if you can slice off the main ganglia or something — whatever it takes to “kill” an oyster? — that might make sense. I guess most people just eat them alive, though. :/

      Dairy is a potential low-impact ( way to get B12 if you don’t want to use supplements, though I have no reason to think B12 supplements aren’t adequate.

      • Yes, dairy is potentially low impact but I think that eating bivalves is more ethically clear-more of a bright line-than eating only dairy since it doesn’t involve raising or killing beings that are inarguably sentient (even at a low rate). I think I’ve only ever eaten one raw oyster in my life so I haven’t thought much about this issue. I don’t really have any data with which to speculate about whether being eaten alive or boiled alive would be worse for the neurons.

      • Dairy is only low impact from an aggregate utilitarian point of view. If one uses “priority” to weight utility, the suffering/loss-of-happiness of a single dairy cow *could* outweigh the deaths of billions upon billions of organism without the potential for self-awareness.

  17. Should pain be the only factor in deciding what to eat? If so, then would it be acceptable to eat other animals if absolutely no pain was caused? For example, would beef be back on the menu if a painless lethal injection was developed to kill cows?

    • Hi Joe,
      While beef cattle arguably live the best lives of animals in confinement for food I don’t know if I would still support raising them for food given a painless death. If you check out my previous blog you’ll see that I’m skeptical that humans are good custodians for animals, especially when those animals will ultimately be killed for food and are raised and slaughtered on a mass scale. That’s why I endorse mussels and in-vitro meat; they don’t involve trusting humans to do the right thing with regard to not inflicting suffering.

      • Hello again. If one of yr main objections to eating cattle is that humans are questionable custodians then, hypothetically, free_ranging game is an acceptable option if killed painlessly..? Also, in yr reply to another point where you state that you are unsure whether killing before consuming oysters/ mussels may have more or less effect on their neurons than consuming them live, doesn’t this imply an acceptance that there *is* the possibility of a detrimental effect on them?

      • hi K. If wild animals live lives worth living then we are shortening their lives by killing (even painlessly) them and thus depriving them more (good) life. Even if we are sparing animals from a horrible death I’m not sure the utilitarian calculus works out. I’m certain enough that mussels and oysters do not suffer to eat them and encourage everyone else to eat them but am I 100% certain? no. And I entertain these propositions because Brian Tomasik has rightly pointed out that even a tiny amount of suffering aggregated over trillions of bivalves might matter morally.

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  20. So, got any recipes? I think a plant based diet + oysters and mussels would be great, but I never ate them growing up, and still think they’re a little gross texturewise. I’m trying to learn to like them, so I am trying to find recipes that are otherwise vegan.

  21. The sentience of mussels or clams is questionable to say the least I don’t think they are vegan per say, as they are still biologically an animal. Similarly many vegans abstain from using sea sponges even though again their level of sentience is questionable, yet they are still biologically animals. Also as vegans we certainly do not require mussels or clams for health, it would also be questionable as to what degree mussels or claims contain environmental toxins.

    All in all I think it becomes a slippery slope into justifying the consumption of other animal products under the pretense that they are not sentient or sentient enough to matter when it comes to consuming them.

    • “All in all I think it becomes a slippery slope into justifying the consumption of other animal products under the pretense that they are not sentient or sentient enough to matter when it comes to consuming them.”

      The entire pretense of veganism in the first place is to protect the sentient, if an animal isn’t sentient how could the rules still possible apply? So what if someone is making an excuse to eat bivalves, if they can’t suffer what does it matter? Someone can easily say, ‘because you are validating that kale doesn’t feel pain you’re justifying consuming them’, That’s really really stupid. Why is animal products the holy in which you cannot touch, even when there’s not the cruelty/enslavement-baggage? Why is there such a moral obligation to eat lifeforms from a specific taxonomy (labeling system)? Shouldn’t we be more worried about the *suffering and *cruelty and awareness to feelings* vs the classification?

      PS: NO reason to eat oysters? Ok, explain to me the natural non-laboratory source that you get your b12 from, please?

      • To reply to your last comment actually mushrooms, potato skins, fermented foods are good sources of B12. Focusing on a non-laboratory source is laughable. Do you eat salt? That is fortified with iodine. Do you drink or eat any processed foods? They are fortified with all kinds of “laboratory produced” vitamins and minerals. Plus, vegan or not, animal products are a poor source of B12.

        The issue is that oysters are not plants. They are part of the animal kingdom. They are not kale. So even though they are not sentient they respond to stimulus. Even tried to open up a live calm? Pretty difficult because it is holding itself shut. You could make the argument that various members of the animal kingdom are not sentient. Chickens do not have a brain like we do, they have a nerve net. So could be categorize them as not sentient? What about primitive species of fish? From another standpoint eating shell fish is extremely damaging to those species whose populations have been in decline since the start of the industrial revolution. By purchasing oysters human beings are contributing to that decline, it is the same as consuming a nonhuman animal from the endangered species list. Again, we do not need to consume oysters for our health. Also are there enough oysters to meet the world’s demand for a source of B12? I highly doubt it.

    • Do I eat processed foods? Yes I do. I’m 17, I don’t have at all any control over my food intake. But my aims are to live a money-free, cruelty-free, off-the-grid lifestyle, and be almost completely self-efficient, meaning not buying foods (processed foods for the matter). And believe it or not, there are a lot of health/ethical vegans who too do not like eating processed and lab-created foods.
      ‘The issue is that oysters are not plants. They are part of the animal kingdom. They are not kale. So even though they are not sentient they respond to stimulus. Even tried to open up a live calm? Pretty difficult because it is holding itself shut.’

      Ever tried opening up a nut? Pretty hard because it’s protective shell is trying to keep predators away. Funny, a lot of plants in the plant kingdom try to ward predators away, perhaps the reason why they evolved anti-nutrients, why some of them have poisonous oils on their leaves, why of them developed sharp prickles on their vines and why some of them close when stimulated by touch? Yeah, plants don’t want to be eaten too, you know.

      If taxonomy is your problem, then you’re not a ethical vegan. You’re a dogmatic vegan, you’re loyal to the *definition, and not the *purpose. You’re one of those vegans who would eat palm oil because it’s “plant-based”, even though it’s directly killing/orphaning millions of orangutans. Please for god sakes, get out of your little box and think about these things rationally. You’re arguing it being inhumane to eat a brainless lifeform (because that’s what all plant/animal/fungi/bacterial life is, lifeforms) based on a intangible classification system that *humans made. That is beyond ridiculous.
      ‘So could be categorize them as not sentient? What about primitive species of fish? ‘

      There is a difference between sentience, and intelligence. Fish (especially) and any other animal in the animal kingdom with a brain, have advanced nervous systems, and can feel pain as much as human can, meaning they deter separate good stimuli from bad stimuli, and have the conscious ability to experience suffering. A brainless lifeform cannot do that.

      As a sidenote, I hope you realize that anyone can use this same argument to argue how cruel vegans are for eating plants.


      ‘By purchasing oysters human beings are contributing to that decline, it is the same as consuming a nonhuman animal from the endangered species list. Again, we do not need to consume oysters for our health’

      Bivalves can be farmed. And it’s not just oysters, there’s clams, mussels, scallops and cockles which can be found all over the world, in saltwater as well as freshwater areas. Bivalves are believed to be a ‘sustainable food source’ like bugs, they can be produced in bulk, with very little food, and energy. Unlike any other animal used for food (including bugs), they have the capability to clean up the water they’ve been farmed in, which mean these animals can be used to fix pollution problems while providing the public a RICHER source of b12, iron, iodine, DHA, and protein, than cows and pigs, WITHOUT the cruelty and environmental baggage.

      Lastly do your research on fermented foods, according to, those claims are nothing but uneducated rumors.

      >>”Because bacteria produce vitamin B12 and fermented foods are generally fermented using bacteria, there are many rumors regarding vitamin B12 being in fermented foods. To my knowledge, no vitamin B12-producing bacteria is required for any fermented food and, therefore, any fermented food that contains vitamin B12 does so via contamination. “<<

      • According to

        “Contrary to the many rumors, there are no reliable, unfortified plant sources of vitamin B12, including tempeh, seaweeds, and organic produce.”

        “Despite the overwhelming evidence that vegans without a reliable source of vitamin B12 are likely harming their health, some vegan advocates still believe that “plant foods provide all the nutrients necessary for optimal health,” and do not address vitamin B12 when promoting the vegan diet.”

  22. Great article! I’ve thought this for about 4 years now but didn’t realise anyone else agreed with me. I love reading about ethical decisions being based on science. Thanks for a great read!

    (posting again because i forgot to tick the box for email follow ups)

  23. Truly an amazing post. I’ve occasionally thought about becoming a bivalvegan, but never made that step because I’ve always given them the benefit of the doubt, as they are part of the animal kingdom. Also, I’m afraid that by making that switch I would weaken my convictions in the minds of other nonvegans. If my passion and convictions towards animals are weakened in the minds of other nonvegans, then it is possible that they are less likely to consider a more appropriate and moral lifestyle (such as the vegan or bivalvegan diets). Therefore, the more utilitarian approach to this issue is to be a strict vegan until the general population understands that it is sentience that makes life valuable.

    • Explain that you only consume ‘non-sentient lifeforms of any sort’, lifeforms without brains, consciousness, and central nervous systems; lifeforms without emotions, thoughts, feelings or intrinsic desires.

      Don’t narrow it down to just the plant kingdom. That’s irrational. Vegans eat fungi and beneficial bacteria (fermented foods) as well as plants.

  24. #3 is an especially strong point. Agriculture inevitably kills insects and other invertebrates that have more sentience than sessile bivalves.

    In a natural system that has evolved through organisms stealing energy at the expense of others, the ethics of eating are not clear cut. The important thing is that humanity considers animal sentience when making eating decisions, as you have done.

    • It’s possible that from a utilitarian point of view, eating sessile bivalves might be among the most ethical foods in much the same way that dumpster meat is almost perfectly ethical.

      I personally don’t eat bivalves largely due to habit, a reluctance to seek out expensive marginal foods that don’t fix bigger ethical questions, and concern about the environmental impact of large scale oyster farms.
      concerns are met I will probably at least symbolically eat oysters un

  25. Pingback: The case for vegans eating oysters | o h , s i e n a

  26. Sounds good, now I cant get by the fact that shellfish carry the highest % of ocean toxins. Guess ill keep stickin to lentils..

    • Rice often contains harmful levels of heavy metals! And yet…somehow…most vegans with a capital “V” don’t complain much about rice-eating vegans.

  27. Pingback: Shucking oysters: A soft start to the kill-to-eat diet | Louise Gray

  28. Pingback: Getting omega-3′s: Science, texture and allergies | Ed v. Food

  29. I only eat shadows, I win…Kidding 😉 I really did enjoy the article though. Oysters are my absolute FAVORITE seafood and I’m so glad that my occasional indulgence [most likely] doesn’t cause them any suffering. Thank you!


  31. Today, I went to the beach with my children. I found a sea shell and
    gave it to my 4 year old daughter and said “You can hear the ocean if you put this to your ear.” She put the shell to
    her ear and screamed. There was a hermit crab inside and it pinched her
    ear. She never wants to go back! LoL I know this is totally off topic but I
    had to tell someone!

  32. I am glad to find your blog and other vegans that are more concerned with SUFFERING and less with DEFINITIONS. I have some things to consider below:

    1) there is record of animals which shouldn’t be able to do certain things, as they contain no brain or other cells we understand them which give them certain capabilities, and yet they do: for instance; slime that has memory, and this (Ripped off another site:) “Although the ameba is a single-celled animal, it does appear to be sensitive to the environment. This tiny animal moves away from light, but it has no photodetectors or eyes. The paramecium, another single-celled animal, also has no specialized sensory structures. However, it avoids cold, heat and chemicals by backing up and moving away.” This would seem to infer that we have no idea at all if the oysters can feel pain or not. however, I’d say its very likely that even if they do its not at all like we experience it (MAYBE). If sessile bivalves shrivel up in lemon juice or jump around in your mouth, it still might not be pain however, as we know many plants also move in such slight manners….what convinced me most about your article is when you said Oysters have no “neurotransmitters or neural firing in response to injury,” so- stick a fork in a live oyster (whose shell is not broken) and it doesn’t even MOVE? Very convincing. however, if that is true, what is causing the squirming and shivers? So, I am almost convinced, but because I am so loathe to chew on pain and suffering and death in my mouth, they won’t be on my plate now (might change my mind later though). Right now I still feel a possibly unreasonable disgust and unease in my stomach at the thought. And yet – that is my criteria for plants; no brain, no movement away from pain, therefore no pain. and if there is pain in plants, go vegan because you will eat way less than a cow will…and you will kill the cow TOO!

    2) Environmental impact: What should be done with all the millions of potential shells?

    3) I have strayed a little from veganism, but not much. I usually tell people “I am vegan but every so often I eat something with a little dairy in it, like a bag of chips or a dessert” however at a restaurant, to clear confusion, and for food safety, I just firmly say “IM VEGAN” (and explain further to my friends later) I’d think oyster eaters could just do the same. as for dairy, I always thought beef was the lowest cruelty animal product as many of them live half their life on a range before the feedlot; I don’t see how dairy is less cruel when it kills a calf AND a mother after she has often been chained up to a milking machine, many become downer cows, and THEN she is slaughtered anyway often for dog food? I dodn’t see how dairy could be kinder – by the way I came up with a solution to ELIMINATE dairy veal (and I also support invitro meat) HOWEVER, vegans and meat eaters alike ignored it – they are too busy fighting to work on solutions together – I sent it to the dairy industry, you can see the idea here: (so this is another reason I am glad I found you, because it sucks being a vegan who is more concerned with suffering than definitions, and finding no other vegans like you out there!)

    4) WORDS: So, I was thinking that this could be considered a new word entirely, not something related to veganism. I’ve been feeling different from other vegans for a while now, and it makes me very lonely. What about a word like “Compassionitarianism” A Compassionitarianist would be someone who sizes up their food based on suffering, not definitions of plant/vs animal. It would be an incredibly arduous task to sum up and size up suffering, but we have time and I think its worth it especially as we expand humanity wildly. Data could be evaluated on food production techniques, which is what vegans want ANYWAY. For instance, a compassionitarian might decide to attempt at all times to eat only greenhouse grown vegetables rather than conventionally grown vegetables, due to the lesser pesticide use, lesser insect and rabbit deaths, etc. Or, one might find that biodynamic gardening produces the least suffering; I really don’t know. but if a word like that caught on and became trendy it might be a great thing for our planet; the idea is to consider our actions for compassion, and not just in what we eat. the word says it all; the word vegan is less blighted nowdays, but still blighted. I know most vegans are incredibly intelligent, so I leave it up to you. There could be raging debates as to what is less cruel, and of course plenty of studies and data needed

    5) I understand your argument about the idea that oysters kill less animals than many methods of vegetable production; however, where does this argument end? Do we then use that to start hunting? (although I’ve made peace with hunters in my own way; finding out deer kill and eat living songbirds made me feel much less sorry for them, and at least they live free, not in captive slavery camps).

    6) the Goddess Artemis (Venus) was a hunter, who only hunted the “fearsome” things. She FIERCELY defended the gentle creatures, and punished hunters who killed rabbits for instance. I feel much the same. It bothers me much less to see a predator get killed and eaten, for it has killed and eaten others, and caused the same pain, than a gentle herbivore, (this is only in the wild; once they are enslaved, even carnivores are 100% innocents). But, killing only killers (carnivores) might have its own drawbacks – they might add things to our world we can’t imagine now. not just eco-system wise – what if a carnivore’s fur DNA ends up being the key to ending a plague? Besides that, even if a world filled with plants and bunnies would be heavenly, we would miss out on the interest and uniqueness, diversity that the carnivores bring. I had to suddenly bring that thought around to meat eating humans, and realized I could not hate them, or else I should hate all the carnivorous animals out there too. But, I still would rather sit down to eat with, hug or kiss, a vegetarian than someone who just killed a sentient being for their greedy little palate. So while I accept it now, it still causes me pain and I’d rather spend more of my time around someone who considers/reduces the suffering they create. This issue is incredibly complex for me now, and painful, but I guess what I am trying to say is, killing a wild scallop, to me, if it is a hunter that hurts and kills others, seems more ethical than it used to even though I still abstain (NO! I AM NOT TALKING ABOUT FACTORY FARMING!)

    7) HEALTH ISSUES: I used to be anemic and went through the heme/vs non heme iron issue. (my mother is also anemic however, and she eats meat). I was able to solve it with taking food grown iron pills – iron grown into algae. Adding copper to my diet, now I dont have an issue with it at all strangely enough. It was like an experience of my early veganism or something. but I do see what you are saying about the potential health benefits of oysters. BUT. What about the health NEGATIVES? Are they also cholesterol causing, heart clogging, etc? I truly love going to the doctor and seeing my RICH deep velvet red blood in a tube swimming in a sea of orangy, fatty meat eater vials. I can pick my blood vial right out of a huge tray for its deep rich healthy color. I enjoy seeing my blood pressure be 104/68 and having them get a little shocked to re-test me. Are there any negatives to health about eating Oysters?

    PS: thanks for your in depth article, the best I have seen on this topic, and the most vegan.

  33. PS: the fact that amoebas can move away from light with no brain, nerves, or senses, might also indicate however, that the oyster shivers are the same thing – just mindless movements. so it could go either way…. it might mean there are senses out there we don’t know how they exist, or that there is movement which is meaningless and contains no pain or sentience

  34. I keep thinking about this (can’t let it go really) and thinking about a creature in a dark shell, it would have no need for memory, and memory/senses might actually make it stop eating = for what kind of creature would want to need sensory input or have memory inside an unmoving, changeless dark shell? In fact there is no need for memory or senses other than a reflex to close shell, for the Oyster, however this is not to say nature is fair; it could have some type of pain just because of being a precursor to other animals which do need pain to survive. However, I really doubt that without a brain or memory, that this is real pain as we understand it. What has been boggling my mind thinking about this, is the applications which might be used for in-vitro meat, perhaps a few neuron free ganglia could be implanted in meat batches in order to make the meat more reactive to electrical impulses and make it “exercise” which is one of the problems right now with invitro meat besides the cost and the nourishment/harvesting of cells not being vegan compliant. Something which has no senses, no pain, no consciousness, no neurons, yet can be stimulated to twitch in order to create as pain free meat as we can for the masses which refuse to give it up.

  35. Pingback: The Dangerous World of Organic Vegan Foods

  36. There are painkillers that work by directly targeting the brain or by preventing pain signals from reaching the brain like paracetamol and cannabinoids.

    Hypnosis and hypnotics work by erasing memory and thus pain is strongly correlated with memory and the brain. Thus, if you lose consciousness even during the most life-threatening operation, you will not remember feeling any pain.

    The evidence, then, suggests that a brain is necessary to experience pain at least as we know it.

  37. “As such, oysters are not considered to have consciousness or to perceive pain.”

    “Considered..” “Do not seem..” Our knowledge is ever evolving. Not until too long ago we believed lobsters didn’t feel pain. Not until too long ago before that, people even considered most animals we know not being capable of feeling pain, or any other emotions for that matter. Why take our chances? Why not decide to go on the safe side for the sake of the animals involved?

    Furthermore, if we reason like this. Why not eat every animal? As long as we find ways to keep and kill them in a non-harmful manner? Your view disregards the vegan notion that any life has it’s own value, not depending on the use the animal has for us. Why take any animal’s life – even if according to the current notion it perhaps may not be self-conscious or capable of feeling (much) pain – unless you really have to? If you are a vegan, then you know you can live a happy and healthy life without consuming animals. Simply put: then…why wouldn’t you? 😉

  38. The article as well as many of the responses seem to be missing the point that vegans do not eat ANY animals or animals byproducts. period! Just because and animal may not feel pain, it’s suddenly ok to eat them? This is ridiculous. EVERY animal deserves to live without judgement from us as to whether they are worthy of being left alone or not. They are not ours – they do not belong to us; they have their own reasons for existing. The fact that we may not understand what that reason is, is OUR problem, not theirs. The vegan message is clear: Stop killing and abusing animals!

    • Just because plants don’t feel pain or think, it doesn’t make it ok to eat them. Every plant deserves to live without judgement from us as to whether they are worthy of being eaten or not. Plants exist for their own reasons.

      Stop killing and abusing plants!!!!

      p.s see how silly this argument is?

  39. Pingback: Ethical Eating: Bivalves | The Urban Altruist

  40. Counter Argument: Plants are not motile and lack any nervous system whatsoever, but laboratory tests indicate that they respond as if capable of feeling pain. One test used an EM detector which showed that they did not respond to threats of harm, but when they followed with an actual cutting of a leaf in half they noticed a spike in response immediately before the cutting took place as if the plant was capable of discerning intent. In another study plants were shown to form a complex communication network utilizing microbes in the soil. A complex network of signals helps to not only transport microbes to the leaves of an infection, but also to determine exactly what the predator is and then send out signals to attract it’s predators. In the roots it was found by video that the root development responds to what is in the soil. Sometimes pulling away from things that cause harm, growing slower in certain sections, faster in others. The movement is completely animal like and it’s response to “pain” rapid.

    The real difference between plants and animals has to do with a fundamental difference between plant and animal cells, but my overall point is that just because something lacks a nervous system or is not motile does not mean it is incapable of feeling “pain”.

    Now, I’m not making fun here, I’m being completely serious. My position is that all life is sacred – both plants and animals. We are animals and we must kill to survive. We may live separate from nature, but we are part of nature.

    My tribe in Canada (I am 1/4 Native. Mother has Native Status. I qualify for it.) lives in an area where, traditionally, agriculture wasn’t possible. It’s cold and the ground is stony. Hunting and fishing was the primary source of food and that practice sustained the people for thousands of years. Many tribes recognize that this act of killing is a “Sin”, but as long as we show respect to what we kill – be it plant or animal – and make full use of it we can be forgiven. What is unforgivable is to kill without purpose. It is wrong, for example, to kill an animal for it’s fur and leave it to suffer. However, it is not wrong to wear fur from an animal that was treated and killed humanly. One might argue a pain and suffering position either way, but how much damage is caused to life in the process of producing synthetic clothing? How many animals were killed or displaced when the farms were established? I feel that it is more important to live sustainably in balance. Sure, that life style cannot sustain us in this day and age – too many people – but those are principles I choose to live by. (for this reason, even though I am a Genetics major, I have claimed a religious exception based on Native tradition to never perform a college dissection. I would not even dissect an oyster or a mussel by this principle.)

    I did however try going Vegetarian many times, and even tried a Vegan diet. The problem I have is that I was born without an appendix. (there is a barium drink that lets Doctors x-ray your organs) I have difficulty fully digesting vegetable protein so I became anemic each and every time. I am still better off with more vegetables than meat, but I would die without it. I am biologically adapted to eating meat. There are heavily processed foods that I might be able to handle, but the environmental impact of the processing feels wrong. Beyond that, is anything really pure? Often times the nutrients used to grow certain things are made of meat, or the thing used to grow the thing is made of meat, etc. Nature is a cycle and a living soil is full of materials from any number of life forms.

    The only natural non-meat food I found that I can fully digest is Spirulina – a Cyanobacteria with protein quality superior to meat and easier to digest. I grow it in an aquarium very easily and it tastes like a sweet cheese, but have you ever looked at them under a microscope? They way they move and interact is amazing. They group together to avoid phototoxicity (too much light can kill them) and after observing them I notice pain like reactions to excessive light, behavior patterns similar to the socialization of a heard animal, they cooperate to eliminate foreign cells that target any of them (which is why the medium remains self sterile with appropriate PH even though some contaminants can grow in it), and in an Agar petri dish I observed that they are also capable of growing in extremely long plant like chains (water currents appear to break them apart), but that they can’t seem to compete against other microbes without that social movement. It appears that all life, no matter how small, is sacred and worthy of respect. Even though a single celled organism does not have a nervous system it has a complex network of signals that allow it to experience the equivalent of pain, pleasure, and socialization. Seeing this does not stop me from eating because I must eat to live, but having respect for this truth allows me to cultivate them in a manually beneficial – rather than exploitative – manner.

  41. Pingback: Where we draw the line: The issue of sentience | veganethos

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