Correlation between the feeding time of the pike (Esox lucius) and the dispersion of a school of Leucaspius delineatus.

The illumination level at which the pike (Esox lucius) eats most Leucaspius delineatus was compared to that at which the school of Leucaspius disperses.The pike easts Leucaspius predominantly when there is little light (50-75% of its entire prey at less than 1 Lux).The school of Leucaspius gradually disperses at less than 1 Lux.A comparison of the results shows that by and large the pike captures Leucaspius at illumination levels at which the school of Leucaspius is no longer completely unified.As both the ability of the pike to catch prey and of Leucaspius to form a school depend on the optic capabilities of the animals it can be supposed that the predator is optically superior to its prey at low illumination levels and profits from this advantage when catching its prey.