Can A Snail Suffer?
Most of us are familiar with clams, oysters, and snails. If we are veg*n, we may decline to eat them, but we probably don’t give much thought to their life experience. Indeed, the concept of life experience for a clam or snail might seem laughable. However, along with other mollusks such as scallops and mussels, they are eaten in large numbers by humans. Sometimes they are eaten raw, and other times they are steamed alive in their shells. Snails are starved and then boiled alive. In addition, researchers use them in toxicology testing, while cosmetic and personal care companies “milk” snails for their mucus, which kills the snail through dehydration.
Obviously, to do these things to sentient creatures is reprehensible. But whether bivalves and snails are sentient is not clear scientifically. Part of the problem is that science still doesn’t define “sentience” or “consciousness”. How does it arise? What are the minimum criteria? Does consciousness exist on a continuum, or is there a clear dividing line? If there is a state of partial consciousness or sentience, who much is enough for a species to be considered worthy of moral consideration?
Brains are expensive in evolutionary terms. If an animal can survive without one, it is functionally unnecessary. And without one, an animal may not feel anything, including pain. Pain cues animals to react to harm, usually by moving away from the source of the pain. Nociception is different from pain perception. Sensory neurons on the animal’s body react to noxious stimuli. Pain requires a brain, while nociception is a lower-level process. If an animal can feel pain, nociception may translate as that sensation. However, animals that lack a brain, such as mollusks, do behave as if they have nociceptors. Snails may have opioid responses and mussels release morphine when confronted with noxious stimuli. Both reactions suggest that these animals do, in fact, feel pain.
While mollusks don’t have brains per se, they do exhibit some nervous system centralization. They have several pairs of ganglia connected to a nerve cord. The organization is complex enough that some neural processing may be possible. The overall number of neurons comes into play as well, but science can’t say how many neurons is “enough” for sentience. Smaller animals may not need larger brains to manage their smaller bodies and thus may achieve consciousness with fewer neurons. Some evidence also exists for the ability of these animals to learn through association or sensitization.
Given how little we currently know about the sentience of bivalves and snails, the author urges us to apply the precautionary principle, and assume sentience until we have more data — failure to do so could result in immense suffering. Even though the science on this subject is limited, advocates can use this review to help question preconceptions. We don’t really know much about snails or bivalves, and we should wait for science to provide more definitive answers.