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First published online November 19, 2007
Journal of Experimental Biology 210, 4150-4158 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.010173

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Predator detection in Lymnaea stagnalis

Michael V. Orr, Malik El-Bekai, Melissa Lui, Katrina Watson and Ken Lukowiak^*

Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada, T2N 4N1

View larger version (8K): [in this window] [in a new window]   Fig. 1. The change in mean (±s.e.m.) righting response time after exposure to pond (PW, 1.66±0.15 min), crayfish (CE, 1.19±0.12 min) or boiled crayfish (BC, 1.5±0.15 min) water (N=36). PW and BE means are not significantly different from each other (P>0.05) but are significantly different (*P<0.05) from CE treatment (repeated measures ANOVA).

View larger version (7K): [in this window] [in a new window]   Fig. 2. The mean (±s.e.m.) time to explore for snails placed in PW after a 2 h exposure to PW, CE or BC. Time to explore in the CE treatment was 17.34±2.01 s compared with 9.23±1.476 s in PW and 11.33±3.018 s in BC treatment (N=54, **P<0.01, one-way ANOVA).

View larger version (8K): [in this window] [in a new window]   Fig. 3. The mean (±s.e.m.) number of elicited shadow responses of snails in the PW and CE conditions. Snails in CE elicited full pneumostome withdrawal more often when presented with a passing shadow than did snails in PW. Specifically, the mean (±s.e.m.) number of shadow withdrawal responses in PW was 1.00±0.09, whereas snails in CE closed their pneumostomes on average 1.60±0.07 times (N=22, **P<0.01, repeated measures analysis).

View larger version (18K): [in this window] [in a new window]   Fig. 4. The mean (±s.e.m.) number of pneumostome openings (A), total breathing time (B) and mean breathing time (C) of snails in each of the three water treatments. (A) Number of pneumostome openings in PW (2.32±0.29) compared with that in CE (3.58±0.35) and BC (2.52±0.30). The number for CE is significantly higher (**P<0.01, N=65) than that for either PW or BC, which were not significantly different from each other (one-way ANOVA). (B) The total breathing time in PW (72.5±9.84 s), CE (109.8±12.29 s) and BC (69.20±10.01 s; N=65). Again, CE results were significantly higher (**P<0.01, N=65) than those for either PW or BC, which were not significantly different from each other (one-way ANOVA). (C) The mean breathing time was not significantly different in any of the groups.

View larger version (20K): [in this window] [in a new window]   Fig. 5. Oxygen consumption of snails cutaneously respiring in either PW or CE. (A) Total averaged data (means ± 1 s.e.m.) demonstrating oxygen depletion in a closed chamber for snails in either CE (top red trace) or PW (bottom blue trace) measured as percentage O2 saturation. The two traces are significantly different (repeated measures analysis for time-linked measurements on each snail, N=9, P<0.001). (B) The ratio of CE to PW O2 consumption for each snail at each time interval, reference line at 0.

View larger version (43K): [in this window] [in a new window]   Fig. 6. (A) Representative electrophysiological recordings from RPeD1 in semi-intact preparations taken after intact snails were exposed to PW (top), CE (middle) or BC (bottom) treatments. All traces demonstrate spontaneous firing activity, and bursting activity. (B) Summary data for mean (±s.e.m.) spiking activity per 10 min (square-root transformed; N=14). Results for CE (3.63±0.93) are significantly lower (**P<0.01, N=14) than those for either PW (8.17±1.40) or BC (5.94±1.20), which were not significantly different from each other (one-way ANOVA). (C) Mean (±s.e.m.) number of spikes per burst. Again, results for CE (2.14±0.62) were significantly lower (**P<0.01, N=14) than those for either PW (8.91±2.49) or BC (8.69±3.65), which were not significantly different from each other (one-way ANOVA).