THE HANS HASS FIFTY
The mesmerising, mysterious spectacle of thousands of fish moving as one can be explained by a few relatively simple rules
It’s a hypnotic, awe-inspiring sight– thousands of fish moving in sync, as if with one mind. Schooling fish is a phenomenon that arises from something known as “swarm intelligence”, in which independent units spontaneously form organised structures or patterns. But how exactly does it work? The process is far simpler than you might imagine.
THE BENEFITS OF LEADERLESS GOVERNANCE
It’s a form of aquatic anarchy – in a school of fish there is no single leader, no one individual controlling or determining the direction or structure of the collective. In a school, decisions are made according to the collective behaviour of self-organised systems. Self-organisation is when structures appear at the global level of a system as a result of the interactions of its lower level components (Bonabeau et al., Swarm Intelligence, 1999); these patterns on the global level emerge as intelligent ones, but are probably unknown to each individual agent. It has been found that each fish is only responding to the behaviour of its nearest neighbour at any one time. Research published in the journal Proceedings of the National Academy of Sciences shows that fish coordinate their movements according to a simple set of rules, using mainly visual clues, and adjusting their position based on that of their neighbours. According to the lead researcher, James Herbert-Read of Sydney University’s school of biological sciences, the rules include accelerating towards neighbours that are far away and decelerating when neighbours are right in front. They also found that a fish only responds to a single nearest neighbour at any one time. So, when any fish finds itself close to a predator, it naturally moves away from it, its neighbours then follow suit, and the information is passed, fish to fish, between the whole school.