Shoaling and schooling Schooling
The largest schools are often formed during migrations by merging with smaller schools. That's about three billion fish in one school. Israel Program for Scientific Translation, translated by Mill H. Halsted Press, New York. These schools move along coastlines and cross the open oceans. Herring schools have very precise arrangements which allow the school to maintain relatively constant cruising speeds. Herrings have excellent hearing, and their schools react very fast to a predator. The herrings keep a certain distance from a moving scuba diver or cruising predator like a killer whale, forming a vacuole which looks like a doughnut from a spotter plane.