Fish might expend less energy swimming in a school than alone, probably by benefiting from wakes created by nearby fish.

Charlotte Hemelrijk at the University of Groningen in the Netherlands and her colleagues modelled the fluid dynamics of two-dimensional schools of animals, using various configurations of fish-like shapes. They found that fish in almost all the arrangements convert power more efficiently into forward speed than do lone swimmers.

In some configurations, this occurs as fish swim behind one another and move their heads side to side. This means that they benefit from wakes from the preceding fish that speed them up, and are not impeded by swirling wakes that would slow them down.

Credit: Bernard Radvaner/Corbis

Fish Fish. http://doi.org/rb9 (2014)