Figure 3.

Gregarious hunting by M. anguilloides. (a) Group of four individuals searching for prey; (inset) size distribution of hunting groups. (b) Tracings constructed from all video recordings of continuously swimming individuals in search of prey. Placement and width of rectangles (coloured differently for unique individuals) indicate time of day and sighting duration for predators composing coherent groups whenever simultaneously recorded. ‘Known’ individuals that simultaneously entered (or exited) the recordist's field of observation, causing gaps in the tracings, were first (or last) seen swimming together in the same general direction and at the same approximate speed. Brief sightings are also shown for ‘unknown’ (i.e. non-focal) groups or individuals (also with distinctive body markings) that were not followed. ‘D’ and ‘R’ refer to stereotyped, rapid departure responses of single individuals upon prey capture and their eventual return to their same group, respectively.