Figure 3. Fish positions within a school.

Top view of a school of 10 fish. (A) Individuals were numbered according to their position relative to the orientation of the school (O_s, indicated by the frontal filled arrow). Fish in the first half of the school (position 1 to 5) were considered to be in the front, while fish in the second half of the school (position 6 to 10) were considered to be in the back. (B) a fish was considered to be at the edge of the school if its tip of the head was at the vertex of the smallest convex polygon enclosing the entire school (1). (C) The four sectors (front-edge, F–E; front-centre, F–C; back-centre, B–C and; back-edge, B–E) were assigned to individuals of the school according to the definitions given for Figures 3A and 3B.