Can Vegans Eat Oysters? Meet the Ostrovegan

Can vegans eat oysters? Interestingly, some vegans think we can. A plant-based diet that also includes oysters is called ostroveganism. The ostrovegan considers oysters ethical to eat for a few reasons. In this article, we’re going to explore these reasons and ask whether veganism is committed to the same conclusion.

We will see that the scientific reasons vegans use to justify the eating of plants seems to justify the eating of oysters too. Let’s get into it.

^{Note: In this article, I am speaking mostly of ostroveganism, and therefore oysters. We do touch upon bivalveganism but the conclusions are not necessarily true for all bivalves.}

At some distant point in human history, an ancestor of ours sat on a shoreline somewhere, peered into the water, and saw an unusual rock with a crack along the middle of it. We can imagine our distant grandparent then spent a good portion of their morning prying and poking away at this rock until, finally, it gave way and opened up before them. Peering inside, what emerged was a slimy, gelatinous-looking blob – the magnificent oyster. What possessed this brave ancestor of ours to then eat this we will never know. Since that time, however, oysters have been on the menu and are a staple for many cultures around the world.

Can Vegans Eat Oysters?

It might seem unnecessary to ask can vegans eat oysters? For most vegans, the answer is a hard no, they look gross.  Oh yeah, and oysters are animals and vegans do not eat animals. Simple. Job done right?  Well, maybe not.

As we will discuss, oysters sit in this weird grey area of the animal kingdom which is extremely difficult to form ethical conclusions about.

If you wind up feeling oysters are ok to eat then you are joining the ranks of a group of people labeling themselves ostrovegans, “ostro” deriving from the Latin for ‘oyster’.

Should we even ask “are bivalves vegan”?

Peter Singer’s Animal Liberation seems to be the first book to ask “are bivalves vegan”. Given their primitive nervous system and questionable ability to feel pain, Singer concluded that it may well be ethical to eat oysters. Since then he has retracted that conclusion but he does admit that he goes back and forth on the issue.

To a lot of vegans, Singer’s position might feel unsatisfying or even aggravating. I mean, is Singer an animal advocate or not? Why not just give oysters the benefit of the doubt and just leave them be?

Well, the vegan community should not reject conclusions it doesn’t like. We should find leaks in our logic. In doing so, veganism eliminates its blind spots and is all the stronger for it.

I believe veganism’s honesty is its greatest virtue. If the science and logic lead us to the conclusion that it is ethical to eat oysters, then so be it. What we do with that conclusion is a separate matter.

Similarities Between Oysters and Plants

It will be helpful if we first establish why vegans consider plants ok to eat and see how oysters and mussels match up to this.  Here’s a table of similarities to help us do this:

	Plants	Oysters/Mussels
Stationary	✓	✓
No Central Nervous System	✓	✓
Not sentient	✓	✓
Can be farmed responsibly	✓	✓
Can’t experience pain	✓	?

We will now briefly go through each point and check for similarities between plants and oysters. We will then discuss whether oysters and mussels can experience pain, which is the key issue here.

Asking can oysters feel pain is, really, the decisive factor on whether they’re vegan or not. (Spoiler: You’re still going to have to come to your own conclusion on this one, keep reading.)

Plants and Oysters are Stationary

When we talk of a creature being stationary, we should really use the technical term “sessile”. Calling something sessile basically means it lacks the ability for self-locomotion; it can’t move by itself. 

The opposite of this are motile creatures, creatures that are capable of moving about.

Plants are sessile, they stay in one spot and don’t go walking around, not much anyway. 

Like plants, adult oysters and mussels pretty much root themselves to one point, normally in coastal areas, and stay there.  Moving about is not their thing. Sure, they can open and close their shells but so do venus fly traps open and close their jaws, or a sunflower turns to track the sun.

A plant is simply responding chemically and automatically to external stimuli without intention and conscious thought.

Oysters, then, seem to be rather like plants in terms of their sessility. They don’t really move about and seem to respond to stimulation in a very predictable, linear way.

The relevance of this is that for organisms that can’t move, the existence of pain states seems kind of useless.  Oyster sessility, therefore, indicates a reduced capacity to suffer. For plants and oysters, it seems evolutionarily redundant to experience pain given they can’t avoid sources of pain in the future.

Plants and Oysters Have No Central Nervous System

Despite their rock-like appearance, oysters are really interesting little creatures.  They not only have circadian and tidal clocks but also a lunar one which keeps them in sync with opening and shutting their shells for feeding^[1]https://www.theguardian.com/food/2019/jan/09/moon-influences-opening-of-oyster-shells.

Oyster reefs also act as brilliant barriers that protect property and shorelines against storm waves, deflecting 76-93% of wave energy^[2]https://www.habitat.noaa.gov/pdf/tnc_oyster_economics_factsheet.pdf.  Neat.

But let’s not kid ourselves. Oysters are relatively simple creatures. Just like plants, they don’t have a central nervous system. They also don’t have anything that resembles a brain and don’t seem to be aware of their surroundings in anything but an automatic response sort of way.

The Bivalvia….nervous system includes two pairs of nerve cords and three pairs of ganglia (Brusca and Brusca 2003). There is no obvious cephalization and the nervous system appears quite simple.

Research Gate ^[3]https://www.researchgate.net/publication/51253778_Nociceptive_Behavior_and_Physiology_of_Molluscs_Animal_Welfare_Implications

A central nervous system is regarded, by most, as the basic requirement for the experience of pain. That is, given pain is a brain state, if you haven’t got a brain/central nervous system, you can’t experience pain.

Standard models of pain say that physical harm stimulates nociceptors (pain receptors) which then send the signal to the central nervous system. This signal is basically “something’s wrong here, do not want” and the pain state is then realized.

While nociception (the ability to send signals in response to noxious stimuli) may be possible without a central nervous system or consciousness, the experience of pain isn’t. If we’re using the word pain in the normal way, anyway.

Nociceptive reflexes and nociceptive plasticity can occur without conscious, emotional experience because these responses are expressed not only in the simplest animals but also in reduced preparations, such as spinalized animals (Clarke and Harris 2001; Egger 1978) and snail ganglia (Walters et al. 1983b).

Nociception without consciousness Crook and Walters (2011)^[4]https://academic.oup.com/ilarjournal/article/52/2/185/659960

Just like plants, oysters do not have a central nervous system. As far as we know, this is a crucial component in the capacity to experience pain.

Plants and Oysters are Not Sentient

Sentience is the capacity to have a subjective experience, meaning to be conscious of sense perceptions. In other words, if you can ask yourself “I wonder what it’s like to be an XYZ” then it’s probably sentient.  

For example, we can easily imagine what it’s like to be another person. We do it all the time. It’s how we empathize. We can even imagine what it’s like to be a different species.

A lot of vegans are, initially, motivated, by slaughterhouse videos. These scenes make us feel great empathy for the animals, seeing their fear and confusion.  Here, we are imagining what it’s like to be that animal. We recognize they have minds and interests that we can empathize with.

But with plants, we can’t.  No matter how hard I try, I just can’t imagine being a lettuce. Plants are not having subjective experiences and so we don’t consider it cruel to slice up a fresh tomato or roast a potato alive.

To illustrate, no one bats an eyelid if you walk over a patch of grass. There is no moral concern for “grass” as such. If you were to deliberately squish a load of ants with your boot, however, even those who are reluctant to assign sentience to insects would say there is a significant moral difference between the two acts.

But can we imagine being an oyster?  Do they have a mind? Are they having experiences?  It seems we are committed to saying no to all of these.

If a being suffers, there can be no moral justification for disregarding that suffering, or for refusing to count it equally with the like suffering of any other being. But the converse of this is also true. If a being is not capable of suffering, or of enjoyment, there is nothing to take into account.

Peter Singer, Animal Liberation (revised edition), Pimlico, 1995

The justification for eating plants can be used to justify eating oysters

That is because, as vegans, whenever the tiresome “what about plants tho” question comes up we usually trot out the line about plants not having a central nervous system and therefore they are unable to experience pain or have any kind of sentience.

If we are going to use this to justify eating plants then it would be disingenuous if we don’t apply the same criteria to oysters as they too don’t have a central nervous system.

By claiming it is ok to eat plants because they lack a central nervous system, veganism seems to justify the eating of oysters.

Oh no! It’s not looking good for our slimy little friends, they seem to have more in common with plants than the rest of the animal kingdom.

Plants and Oysters Can be Farmed Responsibly

Almost inevitably, in the mass production and harvesting of plant-based crops, small animals and insects are killed^[5]http://www.animalvisuals.org/projects/data/1mc.  The amount of creatures killed is but a tiny fraction of that in animal agriculture, especially considering most crops are grown for feeding to livestock.

Nevertheless, currently, with our modern methods, the majority of plant-based farming still leads to the death of small rodents and insects, via machinery, pesticides, and loss of habitat.

The vegan community acknowledges this. Considering the Vegan Society’s remit asks us to avoid harm to animals as far as practicably possible, most vegans are uncomfortably resigned to the idea that even their diet involves some death of animals.

However, in theory – and in some highly regulated situations – plant-based foods can be grown and harvested without any harm to animals.

This might be an ideal, but it is technically possible. In contrast, to eat an animal, no matter what, eventually at least one sentient creature is being deliberately killed.

How are Oysters Farmed?

But what about the oyster?  Can they be farmed ethically?

Well, yes. There are methods of both oyster and mussel aquaculture that seem to be in line with the vegan philosophy.

That is, it doesn’t damage the environment or harm any sentient creatures.  Oyster and mussel “spat”, which is basically their seed, can be cultivated by heat stimulation and then sat in bags a few feet off the sea bed, grown on vertical ropes, or cultivated in tanks. These methods also involve no bycatch.

The EDF and Sea Food Watch (I know, but they seem quite honest about standards) both consider oyster and mussel farming in baskets and rope as sustainable and not environmentally damaging.

In fact, oysters actively filter out nitrogen from the surrounding waters.  Farming oysters also doesn’t require the use of any pesticides or antibiotics which plant and animal agriculture often does.

So, as far as actually growing and collecting oysters and mussels, it seems they may well be even less harmful than growing fruit and vegetables in terms of the number of sentient lives lost.

Detecting Pain in Animals

The go-to definition of pain among scientists is “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage”^[7]Merskey and Bogduk 1994.

In other words, pain is an unpleasant feeling caused by some kind of harm.  Despite not having any direct knowledge, we are really good at detecting pain in other creatures.

We know when a dog yelps that we’ve just trod on its foot and hurt them. We feel bad for wounded animals in nature documentaries and their pain illicits a visceral response in us.

Pain signals are something we are really good at noticing.

We can even detect pain in fish.  One study^[8]https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2003.2349 injected bee venom into the lips of one group of rainbow trout, and plain water into another group.  The group injected with bee venom saw increased heart rate and curiously they began rubbing their lips on the gravel at the bottom of the tank.

I imagine you’re feeling some sympathy for those poor little fish right now because we kind of just know when something is able to feel pain and it bothers us.

There’s also some compelling evidence for our friends the Cephalopods and Crustaceans to show that they feel pain by Advocates for Animals^[10]https://onekindplanet.org/uploads/publications/cephalopods-decapod-crustaceans.pdf. Although the Norwegian Scientific Committee for Food Safety disagrees with this and believes behavior such as a lobster writhing around in boiling water as merely reflexive action^[11]https://www.semanticscholar.org/paper/SENTIENCE-AND-PAIN-IN-INVERTEBRATES-Report-to-for-Somme/6b16c458c4eec3cc163af5f68835ceea1a0f7a10.

Sure guys, ok.

Can Oysters Feel Pain Though?

We’ve established that we can recognise pain pretty well in other creatures and that plants don’t have the right biology to experience pain-states because they lack a central nervous system.

Unlike plants though, oysters do actually have a rudimentary nervous system.  It’s not much, just two bundles of nerves called ganglia, but, hey, it’s more than a plant.

We’re talking about a very basic nervous system here though. This alone isn’t enough to suggest the capacity for pain.

While oysters seem to be excluded from feeling pain, this may not be true for all molluscs.

There is some suggestion that nociception (the detection and response to tissue damage) may indicate pain in blue mussels due to their having opioid receptors^[12]https://www.ncbi.nlm.nih.gov/pubmed/10640698.

In other creatures, opioid receptors are usually a way in which to regulate pain. While this might seem like good news for the blue mussell, there is some evidence^[13]https://www.ncbi.nlm.nih.gov/pubmed/18782062 that the opioid systems in molluscs are a sort of messenger service for their immune system.

…molecular evidence does not yet provide firm support for true opioid signaling in invertebrates.

Dores et al. 2002

It is a safe bet to say that oysters probably don’t feel pain then. The scientific evidence suggests oysters and almost all mussels simply don’t have the apparatus to have a pain experience.  While we don’t know this for sure, it is the logical conclusion.

…there are no published descriptions of behavioral or neurophysiological responses to tissue injury in bivalves.

Crook and Walters (2002)^[14]https://www.researchgate.net/publication/51253778_Nociceptive_Behavior_and_Physiology_of_Molluscs_Animal_Welfare_Implications

Conclusions

This is a really messy one for veganism.  And I, personally, feel conflicted.  On the one hand, vegans are the voice for animals. We represent their interests and defend their rights.

But what if an animal has no interests, what if an animal, like the oyster, is not even “there”, that is, not sentient.

Ultimately then, it comes down to this:  Is veganism a rule you live by, i.e. Do Not Eat or Use Animals, or is it an attempt to reduce overall unnecessary animal suffering?

Should we simply follow the vegan rulebook?

For a deontic vegan who lives by the rule, oysters are out of the question.

And I feel many vegans will agree with this. The oyster and mussel are definitely nearer the grey end of ethics than say, a chicken, but given that we can get along ok without it, give the little guys the benefit of the doubt, leave them be, and stick to the plan: don’t eat animals.

But what if you’re a consequentialist?

That is, what if you believe the ends can justify the means, even in vegan matters. What if the vegan community conceded some ground and showed a begrudging acceptance of oysters as at least more ethical to eat than other creatures?

Conceding that oyster use is morally preferable to eating other animals seems to reduce overall suffering.

For example, oysters could act as a crutch for those who have trouble transitioning to a vegan diet. Oyster use may be justifiable for someone that has allergies which makes it difficult to consume enough nutrients from vegan sources.

Similarly, imagine someone who is very much anti-vegan and is clearly not going to transition to a plant-based diet. This person may genuinely believe we need a source of animal protein in our diet. Encouraging a person like this to limit their animal protein to oysters and mussels seems to be a good compromise.

Are Ostrovegans Still Vegan?

Is this still veganism?  If we stick to the idea that veganism is simply eating only plant-based foods then, no this is not veganism. 

But if veganism is intended as a way to reduce animal suffering then dogmatically sticking to our guns and chastising any notion of oysters being an alternative in some cases could very well cause more animal suffering.

Some people will continue to eat animal protein, best it be oysters, surely.

By admitting creatures like oysters may not matter morally as much as other creatures, veganism appears as a mature, well-developed philosophy.

This does not mean we should eat them, we have no need to. But it might mean we can eat them.

But in debates, conceding oyster use for those who are adamant they need animal protein, you make it harder for them to justify the consumption of cows, chickens, pigs, and other sentient creatures.

So Can Vegans Eat Oysters or Not?

This was longer than I intended. It seems if we want to remain logically consistent, we have to concede that vegans can eat oysters as the very proof that vegans use to justify the eating of plants seems to justify the eating of oysters.

While I still feel uncomfortable outright advocating oyster consumption, I do feel comfortable saying that oyster and mussel consumption is, at least, morally preferable to the use of other creatures by non-vegans. I think this is something vegans and non-vegans can probably all agree on.