Tritonia diomedea showed stronger orientation into flow with upstream prey or conspecifics than into flow without upstream odour sources in the flow tank
| . | . | . | . | . | Rayleigh . | . | . | Paired Wilcoxon . | . | . | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Odour . | Treatment . | N . | θ (deg.) . | r . | zn . | P-value . | 95% CL (deg.) . | Pairs . | T . | P . | ||||
| Prey | Experimental | 9 | 0 | 0.98 | 8.69 | <0.0001 | 008, 352 | 9 | 8 | 0.05 | ||||
| Control | 9 | 342 | 0.78 | 5.42 | 0.002 | 014, 310 | ||||||||
| Conspecific | Experimental | 17 | 357 | 0.96 | 15.7 | <0.0001 | 005, 348 | 14 | 20 | 0.025 | ||||
| Control | 16 | 329 | 0.71 | 8.08 | 0.0001 | 021, 329 | ||||||||
| . | . | . | . | . | Rayleigh . | . | . | Paired Wilcoxon . | . | . | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Odour . | Treatment . | N . | θ (deg.) . | r . | zn . | P-value . | 95% CL (deg.) . | Pairs . | T . | P . | ||||
| Prey | Experimental | 9 | 0 | 0.98 | 8.69 | <0.0001 | 008, 352 | 9 | 8 | 0.05 | ||||
| Control | 9 | 342 | 0.78 | 5.42 | 0.002 | 014, 310 | ||||||||
| Conspecific | Experimental | 17 | 357 | 0.96 | 15.7 | <0.0001 | 005, 348 | 14 | 20 | 0.025 | ||||
| Control | 16 | 329 | 0.71 | 8.08 | 0.0001 | 021, 329 | ||||||||
Slug orientations were measured with (Experimental) and without (Control)prey or conspecifics in the upstream odour stimulus chamber.
The mean headings are relative to flow (θ, r;0°=upstream) while unobstructed by tank walls etc. Rayleigh test z statistic and P-value assess the significance of the mean heading. We also tested if the dispersion of headings around upstream was reduced in experimentals over controls for those animals with unobstructed orientation during both trials (Wilcoxon paired-sample test T-statistic and one-tailed P-value).
Under all conditions, slugs were oriented significantly upstream [95%confidence limits (CL) include upstream], and for both odour types, slugs in experimental trials had significantly lower dispersion than controls, i.e. stronger orientation into flow with upstream prey or conspecifics than without.