Effects of Humidity on Locomotion in the common garden snail (Helix aspersa) Marissa Hackman, Hannah Kienzle, Alanna MacDonald & Jessica Browne

Introduction Taxis vs. Kinesis Dry vs. Humid environments for snails Strategies for water conservation o epiphragm o reducing mucus production (i.e. moving less)

Introduction Purpose To determine how humidity affects the locomotion of the land snail (Helix aspersa)

Hypothesis The snails should show a preference for the moist environment due to the dangers of being in arid conditions More arid environments should result in slower speeds for snails due to lower mucus production and the possible formation of the epiphragm

Methods ●Two main experimental set-ups: 1. Preference Test 2. Kinesis Test Snails soaked in warm water

Test Snails

Methods Preference Test ●Eight 30 minute trials ●Moist, neutral, dry ●Cleaned between trials ●Direction of chambers reversed ●Location recorded every minute

Methods Kinesis Test ●Four set-ups 1. Low Humidity 2. Medium 3. High 4. Control ●Three 20 minute trials ●Snail path recorded

Results - Preference Test Figure 1. Mean ± standard error of average time spent Helix aspersa (N=8) spent in each environment (Moist, neutral, desiccant) ●Significance determined using a chi-square test ● df=2 ●Significant difference between conditions was detected (p< 0.05) ●Spent more time in the neutral environment ●Often stationary when the desiccant section of the chamber ●Epiphragm

Results - Kinesis Test Figure 1 – mean ± standard error of Helix aspersa velocity (N=3) in environments of varying levels of moisture (control, low, moderate, and high). ●Kruskal-Wallis test ○Not significantly different (p=0.183) ●t-test ○Dry and control (p=0.0093) ○Moderate moist and control (p= 0.915) ○Very moist and control (p=0.539) ●Dry condition: completely stopped movement - epiphragm ●Cheesecloth complications

Discussion Why would the snails prefer neutral and dry conditions? This was not consistent with other findings Inherent flaws with the “preference” test Inactivity is more energetically favorable than moving away in poor conditions Suggests differences in kinesis depending on humidity

Discussion Kinesis experiment Snails in low humidity supported our hypothesis and the results of previous studies However: High and moderate humidity did not increase speed Favorable conditions give no incentive to change behaviour

Conclusions and Implications Snails do not move faster in more humid environments, although they are more likely to be active than in drier environments Suggests that desiccant could be an effective means of pest control

Avenues of Further Research Testing movement over a soil substrate Comparing slug and snail behaviour in these conditions