Figure 1.
Graphic demonstration of the measuring of carps’ bearings.
(A, B) Arrows were drawn along the median axes of all the fish visible in the photograph (the arrow axial course was marked unambiguously by the long dorsal fin, its direction by the head position). (C, D) The underlying photograph was removed and replaced by a compass rosette divided radially into 36 ten-degree segments. (E) Each arrow was moved to the center of the rosette and its azimuthal direction was determined by the nearest 10° mark. (F) Mean unimodal, bimodal and quadrimodal vectors were calculated for the photograph.
Figure 2.
Fish alignment relative to water inlet flow.
(A) Distribution of the water inlet flow directions. (B) The photograph mean bearings plotted relative to the direction of the water inlet flow (standardized to 0°). Arrows indicate the mean vector for the distribution, the length of the mean vector provides a measure of the degree of clustering in the distribution. The inner dashed circles mark the 5% significance border of the Rayleigh test; the arrows exceeding these circles indicate significant directional orientation. The bars outside of the circles delimit 95% confidence interval for the mean bearings.
Figure 3.
No fish alignment relative to light.
(A) Distribution of the nearest or the strongest light source positions. (B) The tub mean bearings plotted relative to the position of the light source (light positions standardized to 0°). See caption to Fig. 2 for explanation. (C) The tub mean bearings plotted relative to the magnetic North. Each pair of dots (located on the opposite sites within the unit circle) represents the direction of the bimodal mean tub vector (see Methods). The double-headed arrow indicates the grant mean axial vector calculated over all tubs; the length of the grant mean vector provides a measure of the degree of clustering in the distribution of the tub mean vectors.
Figure 4.
Histogram showing the distribution of individual fish directional bearings in circular tubs.
Note preferential alignment in the North-Southern direction.
Figure 5.
Circular diagrams of tub mean vector distributions demonstrating the North-Southern alignment in carps.
(A) Raw data plot. Each pair of dots (located on the opposite sites within the unit circle) represents the direction of the bimodal mean tub vector. The double-headed arrow indicates the grant mean axial vector calculated over all tubs; the length of the grant mean vector provides a measure of the degree of clustering in the distribution of the tub mean vectors. The inner dashed circle marks the 5% significance border of the Rayleigh test; the bars outside of the circle delimit 95% confidence interval for the grand mean bearing. (B) Scatter plot summarizing statistics weighted by the length of the mean vectors for individual tubs. The position of each pair of dots within the circle represents both the direction and the length of the bimodal mean vector for one tub. The double-headed arrow indicates the weighted grant mean axial vector calculated over all tubs.