Fig. 3
The mean resultant vectors of fish treatment groups before and during water flow stimulus indicates fish with lateral-line organs ablated by CuSO4 or neomycin can still perform rheotaxis.
a Under no flow (t = 0–10 s), groups of lateral line intact (control, n = 248) and lesioned fish (CuSO4, n = 204; neomycin, n = 222; 18 experimental sessions) have a random distribution of individual mean body angles. b, c Under flow, all groups show a statistically significant orientation to 0° ± 45°, but the distributions of the individual mean angles within the groups differ between the initial (b; t = 10–20 s) and final (c; t = 20–30 s) stimulus bins. Each dot outside the circles represents the mean body angle of an individual fish for the 10 s duration of the no flow (a) and flow stimulus conditions (b, c). The grand mean vector for each group is represented by a summary vector with an angle, theta, and a mean resultant length, rho, where the length of the vector represents the distribution of individual angles around the mean angle of the group. The length of the vector ranges from zero for uniform distributions, to one for distributions perfectly aligned with the mean angle. Consequently, the angular variance (1- rho) is inversely related to vector length. Distributions with the same lowercase letter indicate groups that do not differ statistically. |