Schools of fish are able to swim in unison never missing a beat, each moving up and down back and forth, diving and turning as if their motions are set to music, as they were choreographed. They do so to protect from enemies, to better defend their territory in a group and also beleived that swimming close together reduces friction and allows fish to conserve energy.
A complex combination of senses allows fish to achieve those smooth schooling movements; they are able to respond to water movement due to their hair-like receptors (neuromasts) similar to those in the human inner ear. The neuromasts are so sensitive to any change in the water these fish are able to travel as if connected and move as one unit. At one time it was believed a leader in the school directed their movements but is now known that each fish responds to the movements of the other fish; if one swims in a different direction all the others sense it and move accordingly.
(we human could learn so much from fish, dont you think? :-)
“their magnetic sense
tell the birds where to fly,
put the leg of the spider below
magnifier, and you`ll know why
it dont get entangled in its net,
their keen sense of movement
allow fish to swim in unison...
i dont need to know all truth
just caress me with words
i dont question but fear losing you
i dont question but fear losing you”