A fish school is an impressive demonstration of synchronicity.
However, years of studies pose a fundamental question – Do fish save energy by swimming in schools?
Scientists from the Max Planck Institute of Animal Behavior (MPI-AB), Peking University, and the University of Konstanz have discovered that fish save energy by swimming in schools.
The researchers used biomimetic fish-like robots, and they found out that fish can take advantage of the swirls of water produced by those in front by imposing a simple behavioral rule.
By adjusting tail beats in correlation to nearby neighbors, a strategy known as vortex phase matching, robots seemed to benefit hydrodynamically from nearby neighbors regardless of their position.
However, a previously unknown rule, revealed by the robots, was ultimately discovered to be the free-swimming fish’s strategy. The study was published on 26 October 2020 in Nature Communications.
Senior author Iain Couzin said:
“Fish schools are highly dynamic social systems.”
“Our results provide an explanation for how fish can profit from the vortices generated by near neighbors without having to keep fixed distances from each other,” he added.
The Rule For Swimming In A School
The researchers analyzed robotic fish swimming in pairs compared to alone.
Running over 10,000 tests, they analyzed follower fish in every possible position compared to leaders, and then they compared the results with the energy used in solo swimming.
A significant difference in energy consumption for robots that swam in pairs vs. alone was found- The reason is that the fish in front influence the hydrodynamics of fish behind.
The follower fish must match their tail beat to that of the leader with a set lag according to the spatial position.