The Incident

It was 11 PM on a rainy August evening when my partner and I were walking back from a coffee shop in London, and I accidentally stepped on a snail. Its shell shattered completely under my weight, although it was still moving. We thought there was hope for it, and so we gently lifted it with a leaf and moved it off the sidewalk while I frantically searched on my phone for what to do.

What followed was five agonising minutes of research and moral deliberation before we made the decision to euthanise it by crushing it. Nearly every source we found said the same thing: with a completely shattered shell, a snail is extremely unlikely to survive. They are unlikely to be able to regenerate shells that are badly damaged, and without protection for their internal organs, they are exposed to infections and predators. In such situations, they slowly dry out and most likely die a slow and painful death. The “humane” advice^[1] seemed unanimous—euthanise it quickly rather than let it suffer for hours or even days.

After we made the decision to euthanise the snail, I couldn’t stop thinking about it. We both felt the weight of having to make that decision to euthanise it. I spent a while researching—not just about whether we’d done the right thing, but about snails themselves. How they lived, how they died, how many there were. The numbers I found were staggering, but what really got to me was realising this wasn’t some isolated incident.

Dozens of people walk that same sidewalk every day, just as they do countless others, where snails and slugs crawl across the concrete. Just how many snails have been inadvertently stepped on? How many had died there, unnoticed, uncared for, left in agony? As we stood there, an ambulance wailed past, and we thought about how fortunate and privileged we are to be born human. We have sirens, hospitals, and people rushing to save us when we’re injured. They have nothing.

What I also thought about was that somewhere, right now, millions of snails were dying in ways that are potentially far worse—slowly dissolving in salt, being boiled alive in restaurants, suffocating in beer traps that well-meaning gardeners set out.

In the days that followed, I found myself walking differently. I started noticing snails everywhere—on walls, in gardens, crossing sidewalks after rain. Each time, I’d feel this mix of curiosity and dread. Were they suffering? Could they suffer?

I also felt guilty about my selective attention. Why did it take stepping on one snail for me to care about billions of them? I’ve been a vegetarian all my life (and am now vegan), and concerned about animal welfare, yet I haven’t thought about invertebrates very deeply. It reminded me uncomfortably of Peter Singer’s point about proximity and moral concern—we care more about what we can see, what affects us directly.

The snail I stepped on mattered to me because I heard it, saw it, and was forced to confront it. But what about all the other animals I never see? I cried that night. Not just for the snail, but for what it represented: the vast amount of suffering we barely notice in our daily lives. All of this eventually led me down a research rabbit hole, which in turn prompted me to write this post.

What beyond that single snail?

Here’s something that might surprise you: Based on the estimates of Daniela Waldhorn (a key researcher at Rethink Priorities), between 2.9 and 7.7 billion snails were slaughtered for human consumption in 2016^[2]. That’s more than five times the number of pigs killed that year. She also estimates that between 3.8 and 12 billion snails were alive in the farming system in 2016—more than 12 times the number of pigs, though still only about half the number of chickens.

What makes these numbers particularly concerning is how these animals die. Snails are typically killed by being thrown alive into boiling water, where they cook to death. The killing methods vary by region but are consistently brutal. In some regions, snails are often subjected to low-temperature cooking or drowning by being placed in plastic bags or bowls filled with water for at least six hours. During these prolonged deaths, the animals desperately attempt to escape, sometimes abandoning their shells entirely.

If snails are indeed sentient, these methods would likely inflict severe suffering, with the slower ones causing especially prolonged distress. Although Waldhorn suggested that production is expected to remain stable or even decline in some countries—and that significant expansion is unlikely due to the cultural specificity of snail consumption—the global edible snail market has grown since 2016 and is projected to continue growing over the next decade.

Snails’ lives before slaughter are also shaped by their environmental conditions, which can be very harsh. As cold-blooded animals, they are highly sensitive to temperature, humidity, and light, and sudden changes or extreme conditions can quickly make them sick or even kill them. In farms, overcrowding and frequent handling are common, limiting movement, causing stress, slowing growth, and increasing the spread of disease, contributing to high mortality rates.

Their diets are varied but not fully understood, meaning nutritional problems can arise, and poor maintenance or unclean conditions further stress the animals. Snails are also vulnerable to parasites, infectious diseases, and predators, contributing to high mortality rates (as high as 21-70% in breeding snails). Farmed snails are packed together, crushing each other, deprived of all movement, during storage as well as shipping in overcrowded^[3] conditions, also resulting in a lot of them dying. Even under controlled farm conditions, these factors show that snails live fragile and often precarious lives long before they are killed for human consumption.

Unfortunately, snails killed for food are only part of the story. The boom in snail mucin (the slime produced by snails) cosmetics, marketed as trendy skincare, presents a new concern—this growing industry may drive increased snail farming even as food consumption declines. The global snail mucin market is currently estimated to be somewhere between $750M and $1.56B, and is projected to continue growing (to up to $3.4B) over the next decade.

The collection (called “milking”) methods for this mucin are particularly troubling: while some farms allegedly use natural secretion methods that don’t stress the snails (though with lower yields and longer collection times), the increased market pressure has driven most producers toward more aggressive techniques. These include electrical stimulation with voltages up to 1000 volts, jabbing with sticks or needles to double the mucus yield, spraying with water jets, or using salt solutions that osmotically dehydrate^[4] the snails, which could also lead to a significantly decreased heart rate.

Some producers spray chemicals like citric acid and ozone, while others crack shells open to access the soft bodies, forcing increased mucus production. These practices are designed to cause discomfort, as certain types of mucin are only produced when snails are distressed. The most extreme methods—vibrational, ultrasonic, or excessive electrical stimulation—often kill the snails outright. All these aggressive techniques trigger clear stress responses, including shell retraction and excessive mucus bubbling. While we lack reliable data on exactly how many snails are used for cosmetics, the rapid growth of this industry suggests that even as fewer snails die for food, millions more may suffer for skincare—and unlike food production, where death is at least the endpoint, cosmetic harvesting can subject snails to repeated extractions over their lifetimes.

Do snails suffer?

When people hear about snail welfare, the first objection is usually: “But do they even feel pain?” It’s a fair question, and the answer, based on current evidence, seems to be: probably yes, though we can’t be certain. Philosophically, they have attracted some attention as an edge case in discussions of consciousness.

Consider the evidence:

• Research shows that snails find heat intensely aversive—when exposed to temperatures of 40-52°C, they immediately lift their bodies away from the heat source (nociception^[5]).
• More tellingly, when given opioid painkillers like morphine, snails tolerate heat for longer periods, just like mammals do. When these painkillers are blocked, their heat avoidance returns to normal.
• A study also found that snails show long-term memory of negative experiences. When researchers applied an unpleasant substance (quinine) to snails’ heads, they remained extra defensive for more than 24 hours afterwards. They became more sensitive to any potential threats and reacted more strongly to touch, especially in the area that had been hurt. After three days, this heightened sensitivity spread throughout their entire body, suggesting they can remember and learn from experiences in ways that affect their future behaviour. Similar memory formation has also been observed in pond snails. This likely indicates that snails don’t just have simple reflexes—they can form memories that alter their behaviour long-term, which is what we might expect evolutionarily if they experience something aversive (akin to pain) that helps them learn to avoid future harm.
• Snails have nervous systems that might be complex enough for consciousness. While they don’t have brains like we do, they have clusters of neurons (called ganglia) connected together that perform similar functions. Garden snails have about 60,000 neurons total—far fewer than a dog’s ~2 billion or an octopus’s ~500 million, but potentially enough for basic sentience. Smaller animals likely need fewer neurons to accomplish the same tasks because their nervous systems are more compact and efficient, making it difficult to rule out consciousness based on neuron count alone.
• Scallops, which belong to the same phylum (Mollusca) as snails, exhibit increased heart rates in response to predator cues—potentially a sign of fear and an indicator of sentience. However, given the wide (morphological) diversity within this phylum, it is difficult to determine the extent to which such findings can be applied to snails.

Despite all this evidence, uncertainty remains about the extent and nature of snail sentience. The lack of research on invertebrate sentience/suffering is surprising, given that they make up 99% of the world’s animals.

Why should we take this (and more) seriously?

Although uncertainty remains regarding snail sentience—and invertebrate sentience more generally—this uncertainty should not lead us to dismiss the possibility. As Hayley Clatterbuck from Rethink Priorities suggests, even though small invertebrates (e.g., snails, slugs) have relatively low probabilities of being sentient, their sheer numbers mean that actions affecting them can have enormous expected value. What is clear is that the potential for vast suffering is significant, and the most responsible approach is likely to err on the side of caution by avoiding harm to these animals.

Marcus Davis (CEO of Rethink Priorities) puts it bluntly: “We should stop boiling things alive. It’s such a low bar, but given that there’s a reasonable chance of various creatures being sentient, it seems wildly irresponsible to boil them alive.” He estimates snail sentience probability at around 5%—and as he points out, you wouldn’t take a 1 in 20 chance of setting a human on fire. While this analogy simplifies inter-species comparisons, the core principle remains: boiling potentially sentient creatures alive seems ethically indefensible when alternatives exist.

That framing stuck with me. If the suffering of a single snail can feel so troubling under even a relatively low chance of sentience, what happens when we scale that concern up to the vast world of invertebrates more broadly?

Consider the sheer scale of invertebrate life. There are approximately 10^18 insects and other small invertebrates in the world right now. As Bentham’s Bulldog put it, if you were to live the life of every creature that has ever existed, almost all of your time would be spent as an invertebrate. Every second, hundreds of billions of these creatures die, many in ways that—if they can suffer—involve extreme pain. When confronted with numbers this vast, it’s easy to feel paralysed by the impossibility of addressing such suffering, or to struggle even to comprehend the scale.

But perhaps that’s precisely why targeted interventions become so compelling. Speaking of, Bentham’s Bulldog also likes incessantly promoting the Shrimp Welfare Project, proposing a s(hr)imple thought experiment illustrating its importance: if you came across 1,500 shrimp about to be slowly frozen and suffocated to death, and you could prevent that agony for one dollar (via a machine that stuns^[6] them unconscious first, sparing them 20 minutes of suffering), would you? I expect you would—it’s hard to justify saying no. This is exactly what the Shrimp Welfare Project accomplishes with every dollar donated.

He also makes compelling arguments about why we should care about shrimp (and more generally, invertebrate) suffering. First, he points out that extreme suffering is bad^[7] regardless of who experiences it—what makes pain bad isn’t our species or intelligence but what the pain feels like. Second, he argues that even with uncertainty about sentience, the sheer scale tips the balance: if there’s even a 10% chance that invertebrates suffer, the large numbers of them experiencing potential agony outweighs the suffering of far fewer mammals. Third, he notes that our intuitions about invertebrates are unreliable because we have no natural empathy toward creatures that look so different from us—but this aesthetic bias isn’t a valid moral reason to dismiss their potential suffering. If anything, it is a reflection of our psychological limitations, not their moral status.

This reasoning extends beyond just shrimp to all invertebrates, including snails. The philosophical argument is straightforward: if suffering matters morally, and if there’s a reasonable chance these creatures can suffer, and if they exist in astronomical numbers, then their aggregate welfare becomes a very important (yet neglected) moral issue. Even if you’re sceptical, the asymmetry of risk is clear—if we’re wrong to dismiss them, we’re ignoring suffering on an almost incomprehensible scale.

My accidental stepping on that snail not only made me think about human-caused harm, but also about how invertebrates and other wild animals routinely suffer—often far more severely—from the forces of “mother” nature itself, independent of human action. The number of wild animals far exceeds farmed or domesticated animals. They face predation, parasitism, disease, starvation, and environmental extremes, with most living very short lives. The romanticised view of nature as a harmonious balance ignores that for the vast majority of wild animals—especially invertebrates—life is, to borrow Thomas Hobbes’ phrase, “nasty, brutish, and short.”

This natural suffering might seem beyond our moral responsibility, but as wild animal welfare advocates point out, something being natural doesn’t mean it is good (e.g., we work on eradicating diseases even though they are “natural”). Although wild animal welfare seems less tractable and intervening in ecosystems carries risks of unintended consequences, this doesn’t mean we should ignore wild animal suffering entirely.

In fact, recognising the suffering of other creatures in both human-controlled and wild contexts expands our moral circle in important ways. It challenges us to think beyond the convenient boundaries of direct human causation and consider suffering wherever it occurs. The field of wild animal welfare remains extremely neglected, but promising areas for work are emerging, such as vaccine programs for wild populations, animal contraception, and helping wild animals affected by weather-related events.

What can we actually do?

The good news is that helping other creatures doesn’t require revolutionary changes to our lives. Here are some concrete actions (at varying levels) we can take:

• Watch where you walk, especially after rain, when small creatures like snails and slugs are most active (especially around green/muddy areas).
  • If you ever happen to accidentally step on a snail, as I (sadly) did, this resource may guide you toward the best way to help.
• Avoid purchasing and/or using products containing snail mucin. Consider vegan or cruelty-free alternatives instead.
• If meat or dairy are a part of your diet, this is a good guide on practical steps you can take to reduce animal suffering caused by factory farming (without going vegan).
• If you garden and are trying to manage snails/slugs, consider humane alternatives to salt or chemical-based pest control, traps, or hand-picking, as these cause them great distress and often kill them in a slow and agonising way. Instead, consider integrating them into your garden!
• Support research into invertebrate sentience and wild animal suffering. Organisations like Rethink Priorities are working to better understand which animals can suffer and how much. The Welfare Footprint Institute is also working on various research projects quantifying animal welfare to inform policy and related decisions. Here’s their blog!
• Fund^[8] effective organisations. While there’s no “Snail Welfare Project” (yet), groups/organisations like Wild Animal Initiative, Animal Ethics, and the Shrimp Welfare Project work on invertebrate welfare and wild animal welfare more broadly. Less than 1% of funding in the effective animal advocacy community goes toward invertebrate welfare. Raising that share is important for advancing our understanding of invertebrate sentience (given the uncertainty) and exploring how tractable it is to improve their welfare. Donate!
• Share information about invertebrate welfare and wild animal suffering with others around you (friends, family, colleagues, etc.). Most people have never even thought about this before, so yes, you might come off as a little “weird”. But if looking unusual gets even one more person thinking (or acting) on this issue, that’s a trade well worth making. Also, don’t be afraid to lean on a bit of peer pressure if you think it’ll work.

Final thoughts

While researching this post, each new piece of information about invertebrate sentience/welfare felt like another weight added to my conscience. But (fortunately) it wasn’t all despair! I also came across people working on these issues—organisations developing humane alternatives, and researchers seriously investigating invertebrate sentience. There was something oddly comforting about knowing that there are others who take these creatures seriously.

While I don’t know what this post will ultimately achieve, I hope that, at the very least, it encourages people to tread a little more gently on the world beneath their feet.

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   In addition to online sources, we also consulted ChatGPT by describing the situation in detail and sharing a photo of the snail. The response was consistent with what we had already read: euthanising it was the most humane thing to do. Since the snail had already been in that state for a few minutes, we felt it was important not to delay the decision further and act quickly, in order to avoid prolonging its distress.

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   These numbers have only risen in 2025

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   Can be seen in the images here

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What this would feel like for humans

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However, nociception by itself is not indicative of pain

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A similar water stunning technique is proposed (and being tested) for land snails to reduce slaughter suffering

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As Jeremy Bentham said, “The question is not Can they reason? or Can they talk? but Can they suffer?”

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