EDIT: The following focuses largely on Helix aspersa as the snail I will be using for this experiment. However, due to environmental conditions of the new location and access/information, I will be using the snail, Cepaea nemoralis.
Cornu Aspersum. Helix Aspersa. Garden snail. I always liked snails as a kid. I thought they were adorable and interesting and I’d find them and watch them and pick them up and put them back down. I would lose myself imagining their little worlds as I watched. As an adult, I knew I had a fascination with molluscs. However, it had to do with the intelligent cephalopods in particular; otherwise, I was pretty detached aside from the inner debate as to whether or not I could eat bivalves (they don’t have a “brain” but they do have neurons – can they perceive pain? Probably not, but still…?).
The fascination with the garden snail was reborn when Drew and I found one outside our apartment. I’d seen them before around there and thought they were great; they were way bigger than the tiny, flatter ones I found as a child living in the Houston area. The one that we found seemed to be in a less-than-optimal location and we weren’t sure how it would easily access food or water. We filled up a plate, took it off the concrete and put it on the plate, and the snail emerged from its shell and seemed to bask in the presence of the water. We immediately began looking stuff up and found out that they ate dandelion greens. Easy. We got some and put it on the other side of the plate. The snail immediately started moving toward it. Fascinated, we read some more. Apparently snails have a pretty good sense of smell. The tentacles on their heads (the two that look like antennae and the two that seem like they’d be part of the mouth) serve for smell, primitive sight, and tactile feeling.
We continued to read and found on some forums that people claimed that their pet snails could hear and recognize them and would move toward them. As snails have no ears or similar structure (other than the shape of their shells being similar to our cochlea), those posts got wide criticism. But I (and I wasn’t the only one) wondered if they felt vibration from someone coming in or perhaps speaking, especially if they’re kept indoors with a very stable, predictable environment. Sound is, after all, vibrations that we have specialized equipment to translate into what we call “hearing”.
“In his rooms sat 4 pianos without legs and piles of manuscripts that no one was allowed to touch.. To feel the vibrations better, Beethoven composed music seated on the floor at a legless piano. He often worked in his underwear, or even naked. If friends came to visit him when he was composing, he completely ignored them.” –Source
Whether or not that quote is true, it shows how feeling vibrations translates. Beethoven was deaf, yet used vibrations nonetheless to hear the music he wrote.
If not hearing, as they have good sense of smell, I wondered if they couldn’t just smell the person and associate them with where their food comes from. If snails do seem to “hear” based on vibration, whether or not they could determine one individual from another or if it’s generalized is questionable as well.
Garden snails have been widely studied because of their large neurons. It has been shown that snails in the Helicidae family have memory such that conditioning using repeated stimuli shows evidence of learning and memory. Research shows a lot more than that, but learning and memory are specifically what I’m interested in. [Additional sources here, here, and here, and work by Nikitin VP concerning snails]
This gave me an idea. To test whether or not the snails may be able to discern different sounds, I would have food drop in to their habitat on the left or right side, corresponding with a different frequency. Once they were given time to establish that one sound meant to go to the right side of the habitat to acquire food and the other left, we’d change it to just playing the sounds and see to which side they’d go. If they went to the side of the habitat that we’d taught them to associate with the sound, it would provide evidence to support that the snail can sense vibrations and differentiate between different ones.
This experiment will not be able to begin until after I move, in late July or August. In the meantime, I will keep you up to date with the experiment setup. In the next post(s), I will discuss snail habitats, how I intend to set mine up, how many snails I intend to work with and how I intend to procure them. And, I’ll set up specific parameters to the best of my ability to minimize variables in the test. Once the move is complete and I’m able to start setup, I’ll proceed further.
Beyond answering the question of if snails may be able to associate certain sounds with reward, I hope to gain more experience with setting up and implementing experiments and begin wandering into the zone of neuroscience-in-action to complement my reading about consciousness and the brain. In other words, I intend this experiment to have far more rigor than my last. And I hope to learn more than just results to a hypothesis.
Whimsy will always be in my heart, but the true magic comes from science.