The Effect of Inclines on Snail Locomotion 

Introduction

This research project questions the effect that inclines have on snail locomotion. The topic of snail motility was decided on as a result of curiosity from learning about the method of locomotion snails' use. Snails, invertebrate animals in the phylum Mollusca and class Gastropoda, have both aquatic and terrestrial species, however terrestrial snails will be focused on in this project. For life on land, snails acquired adaptations that benefited their survival and ability to thrive. (1. Nordsieck 2011)Motility in land snails revolves around possession of a foot, an organ specialized for locomotion.

The foot is flat on the bottom, and is attached to the snail’s head at the anterior end. The foot acts like a muscle, and its contraction causes a wavelike propulsion that allows the snail to move forward. This form of movement is known as crawling. One land snail species, the Roman snail, was found to have an approximate speed of about 7cm per minute. (2. Nordsieck 2011)

Snail locomotion can be tracked due to the slime like trail of secreted mucus left behind as they move. However, it was only recently discovered that this mucus is not required for horizontal movement to occur. “We were surprised to find that the special mucus properties weren't essential. Mucus is still very important, but we found that there are other mechanisms that the snail uses to generate the traction to move forward. ” This quote by researcher Janice Lai, the Stanford graduate student whose research uncovered this interesting piece of information about land snail motility.

Her research proved that although the slime secretion provides protection when travelling on a rough surface, and adhesion that allows movement for travelling vertically or upside down, the secreted mucus was unnecessary for horizontal movement to occur. The concept of slime being an assistant to movement at certain trajectories resulted in the specific question of this project; of whether the velocity at which a snail can move will be affected by the addition of an incline. (3. Sandeep 2011)

Question, Hypothesis, and Predictions

How is the locomotion of snails affected by the presence of an incline? I hypothesize that as the trajectory in which a snail travels gains a vertical component, where the incline increases, then the velocity at which the snail can travel will decrease. Based on research, I predict that the snail will move the most efficiently when travelling across a horizontally flat surface, and the velocity will be affected negatively as the path along which the snail travels becomes more inclined. I also predict that the snail will travel with the lowest velocity along a completely vertical path, at a 90 degree angle in reference to the flat ground, compared to a horizontal path. The graph shown in figure 1 are the results I expect to see. With the initial unknown time when moving on a horizontally flat surface of angle 0 degrees, I expect the time elapsed to increase as the angle at which the snail is moving increases. This can be used to find the snail’s velocity, as each stage of the experiment will be performed at the same distance.

Therefore, we can use the equation of velocity = distance/time to find how the velocity changes at different incline angles. MethodsControl: We will use a horizontal surface, at a 0 degree angle. This will allow us to compare ourother angles to the control. We will measure the rest time for each snail between their trials, preventing our data from being contaminated by the snails’ endurance. We will use snails of similar masses, allowing up to 0. 25g difference. Replication: We will replicate each incline with each of the three snails, including the control, so as to have more data to compare, allowing a more conclusive result. Randomization: We will perform the experiment in no particular order of inclines.

Inclines: We will use the same material to create each path with equal width and length.

Distance: We will mark out the same distance (10cm) on each path, so that we can measure the times and compare them without error. Time: We will record the time taken for each incline with each snail in an observations table. Tentative TimelineWe will perform all experimentation required for the project during lab #8, bringing or acquiring all equipment, supplies and organisms for that day. Before week 9, we will analyze our data, and start our project summary, and before week 10, we will finish our project summary and create a project presentation.

Tasks

During the experimental process, there will be about 8 tasks to complete, which we will divide evenly between us. These tasks are: weighing the snails and recording their weight, creating the incline angles, making the paths for the snails to follow out of cardboard, measuring the elapsed time to reach the destination, timing the minimum snail rest time, recording the time data for each incline, solving for the velocities of each incline, and cleaning up the supples/materials. Following the experimentation process, we will work together to analyze the collected data, and produce a summary of our research project.