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
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
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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).
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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).
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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).
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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.
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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.
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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).
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© The Company of Biologists Ltd 2007
