In an effort to find out if snails may be able to discern different frequencies and in response to people’s claims that their pet snails can recognize their individual voices, I will perform a test that involves attempting to train snails to go left or right depending on the frequency played using a food reward. This experiment will not validate whether or not snails can differentiate people’s voices as that is out of the scope of this test, but it may indicate the possibility of snails being able to hear, giving insight for further exploration into the nature of hearing, despite lacking the biological infrastructure typically associated with hearing.
Here are the plans for the setup:
Ideally, I will have 10 or more snails from the species Cepaea nemoralis. Aside from the four already collected, I have not had good luck finding more. One of them I may not be using as it seems far less vigorous than the others. However, if I am unable to find 10 healthy snails, I will proceed with the ones I have at the beginning of next week.
Each snail will be kept in isolation in a light blue, clear plastic bin with dimensions of 12.88” x 9.13” x 5.14”.
The bins will be placed next to each other on 4 shelves. In each bin will be a comparably-sized, washed rock for hiding (it must be washed or they may eat whatever is on it). While on the shelves among the others, each snail’s habitat will be spritzed with water at some point in the morning and at night to ensure ample moisture. Watering will occur independently of food distribution. The snails will be kept in a closet to attempt to maintain approximate temperature and consistent light/dark periods of 12 hours each. Food distribution will occur twice a day, once shortly after the dark hours end and will be signaled by the opening of the door (to somewhat simulate dusk and dawn, when snails are naturally most active) and once at the end of the day, before “dark”.
Prior to the start of the experiment, the snails will be moved to the bins and given 48hrs to adjust while weight and size measurements are taken. They will be fed ad libitum during this time. After this period, the bins will be washed and the snails will endure a 24 hour fast before the experiment begins. Once the experiment begins, the snails will be fed twice a day and fast the rest of the time. The amount of food should be sufficient for their size and will include herbs, egg shell, carrot, and other veggies to maintain a varied, calcium rich diet. Their weights and the weight of their food will be recorded using a Smart Weigh ZIP300 scale.
They will each be tested separately. During testing, each snail’s bin will be brought to a different room, the lid of bin will be opened 1/3 to 1/2 of the way. On the lid will be sitting a cell phone (type undecided) that will be used exclusively for this experiment during the experiment’s duration. The sounds will be transmitted from the phone’s speakers at the same frequencies and amplitude for each snail.
Built using plastic popsicle cups and a little hackery, a handmade Y-maze will be used. It will be enclosed to prevent the snails from climbing over it, but ventilated. Before each food distribution, the maze will be placed in the habitat, and each snail will be placed at the beginning of the maze. After each snail is tested, the maze will be cleaned so that the chance of mucus trail following is minimized. After the snail is given time to feed, their bin will also be cleaned to remove food remnants.
Food will be distributed using a plastic serving spoon attached to an extension to prevent them from smelling the direction of my grubby mitts. They may be able to smell the plastic of the tool or feel the air movement, but the likelihood may be less as they live in plastic containers and their environment has already been disrupted.
Experiment timeline and description:
During the learning period of 4 days in an effort to allow them long term memory formation (information of definite time taken to form long term memory was difficult to find (the potential result of this is discussed in the foreseeable issues section of this post)), each snail will be taken into a different room in their bin and each will be tested separately. The maze will be inserted and snail positioned at the beginning. The lids will be left off the bins 1/3 to 1/2 of the way for food distribution and as a safe location for placing the cell phone that will produce the sound. Once the lids have been moved, the sound will be played and food will be dropped into the corner of the bin intended to be associated with it. The sound will play until the snail finds the food. Each snail will be timed. While they eat, the y-maze will be removed and they will be given time to feed while the next snail is tested.
For 130Hz, or a C note, which is in the average range of a male voice, the food will be distributed on the right side of the bin (from the experimenter’s point of view/end points of the maze). For 220Hz, or an A note, which is in the average range of a female voice, the food will be distributed on the left side of the bin. Both sounds will be calibrated at the same decibels. For each test, the frequency will be selected randomly, so they may or may not be different than the time before. [Frequency info found on Wikipedia and note equivalents found here.]
Once the experiment has begun, the conditions will be the same except that the sound will be played but no food will be distributed until the snail has chosen a direction in the y-maze, should movement or direction occur. Whether or not movement occurs and in what direction will be recorded. If movement does occur, which side of the maze they enter will be recorded and food will be distributed either way in the designated area. Any change in their direction will be recorded. The testing will go on for 3 days, providing 6 data points for each snail.
For the control snails (number to be determined), they will continue to be fed from the start of the sounds and measurements will be recorded.
Foreseeable issues with test:
When a snail is being tested, the will be separated from the rest of them; however, because there is imperfect sound-proofing, it is still possible that the other snails will be able to sense the frequency coming from the other room and this may be confusing. Also, the frequency may manifest at other times of the day unintentionally and that too could be confusing.
Because I will be setting up the snails, playing the sounds, distributing the food, and recording the times, there is plenty of room for error and unintended bias. I will try to be exact, but I don’t fully understand the scope of subconscious influence in this case, which should be considered.
The maze is hand made so is unlikely to be perfectly symmetrical or perfectly smooth which could influence decision-making for the snails.
There may be conflicting or distracting vibrations from other goings-ons in the world.
There is intelligence differentiation within a species and the snails I have may not learn quickly enough.
This particular species may lack the ability or are slower to learn in general. There have been memory tests done on other snails (such as Lymnaea stagnalis here, here, and here and Helix aspersa here and here), but none that I found on Cepaea nemoralis. Also, more evidence has been shown with remembering negative events than positive ones.
There could be coincidence afoot. Hence, there is always the need for more testing and removal of variables, confounding or otherwise!
Featured photo is of Smotchkkiss exploring outside the bin!