What questions am I trying to answer? How will I go about answering them?
- For a snail of a given size going 1st, does the presence of food affect their behavior?
- For a snail of a given size going 2nd, does the presence of food affect their behavior?
- When no food is present, does order affect behavior for snails of a given size?
- When food is present, does order affect behavior for snails of a given size?
- I categorized snails by their shell diameter: large (2.0-2.2 cm), medium (1.0-1.5 cm) and small (0.4-0.6 cm). For all trials, the snails’ start location was in the center of a 35.5 x 35.5 cm glass plate. I placed the first snail on the start location and then recorded its position every 10 seconds for 20 minutes, using a colored grid beneath the glass as a reference. I then removed the first snail and repeated the process with a second snail.
- I ran one set of trials without food and another with food. I placed food (fish flakes) on an edge of the glass plate and rotated the food’s location 90° for each subsequent trial as a control for any environmental effects.
- I counted stalls (the number of 10-sec observations before the snail left the start location) and pauses (the number of observations for which a snail had not moved from its just-previous location after leaving the start). I denoted these using dots.
- I measured the total distance traveled, linear distance traveled (distance between start and end location), and final distance apart (the distance between the two snails’ final locations). I calculated the sinuosity of each snail’s path by dividing total distance by linear distance.
- Statistical analyses were performed in R. Lindsay Nason helped me analyze stalls and pauses using the quasi-Poisson distribution; path length, sinuosity, and final distance apart were analyzed using normal distributions. When necessary, data were transformed to meet the assumption of normality.
- large x large (2.0 cm – 2.5 cm)
- medium x medium (1.0 cm – 1.5 cm)
- small x small (0.4 cm – 0.6 cm)
Below is a link to a paper that advocates for the use of computer programs (like ImageJ) to accurately measure the diameter of snail shells.