Since as long as I can remember, nature documentaries and textbooks have said that flocking birds and shoaling fish gather in large coordinated groups to protect themselves from predators. That explanation makes complete sense. After all, many eyes can spot danger more easily, and many bodies can confuse the senses of hunters. But common sense often leads us astray in biology, and very few people have checked to see if collective motion does offer safety from predators.

Ioannou currently works at the University of Bristol but he did his fish experiments in the lab of Iain Couzin. Couzin and others have used computer simulations to reproduce the complicated movements of real animal groups. Their virtual flocks and shoals can