The way fish move has a significant impact on how noisy the school is, according to a new study. Engineers say the finding could lead to the development of stealthier underwater vehicles. <\/p>
Engineers at Johns Hopkins University have found that the formation of a school of fish significantly affects how noisy it is. If they move together “in just the right way” a school of seven fish can sound like a single fish.<\/p>
Ji Zhou and Rajat Mittal, the authors of the new\u00a0study<\/a>\u00a0published in the journal\u00a0Bioinspiration & Biomimetics<\/em>, are part of a research group interested in fluid dynamics and the biomechanics of bio-locomotion. \u201cThis includes flight of butterflies, mosquitoes and moths, flying bats, and swimming animals such as dolphins, humans and fish,\u201d says Mittal.\u00a0<\/p> They were interested in how fish benefit from swimming in schools: is it more efficient, can they swim more quickly and do certain formations give more advantages? <\/p> Mittal and his colleagues were intrigued to find out the degree to which school configuration impacts underwater noise, and thus the safety of fish around predators such as sharks, who have very acute hearing.<\/p> To answer this question, they set up computer models to simulate how noise is created if fish swim together in different configurations. <\/p> \u201cWe started by creating a 3D model of a common mackerel, incorporating dynamic movements to simulate natural swimming behaviour,\u201d says Mittal. This allowed them to see what happened with different numbers of fish swimming in different positions. <\/p> When they evaluated the intensity of sounds in these different scenarios, they found that how closely fish swim together and how they\u00a0sync their tail flapping has a significant impact on how noisy the school is.\u00a0<\/p>