How Do Fish Swim in Schools?
Almost all species of fish travel in schools. But have you ever wondered why they do this, or how they're able to achieve such uniform motion? Few groups of animals are able to move together so well, with the possible exception being large flocks of birds. So how is it that fish are able to accomplish this amazing feat?
Other People Are Reading
-
Why
-
Fish travel in schools because of the old rule that there's safety in numbers. When a predator wishes to attack, a fleeing school of fish is much more confusing to the predator, and therefore much more likely to survive, than a single fish that is easy to keep focus on. A school of fish can also gang up to defend themselves against a predator whereas a solitary fish would be able to do nothing but try to swim away. Fish who travel in schools are also able to move more easily, due to the effect each fish has on the water around it; each fish is better able to combat water friction because of the currents created by the others' motions.
When
-
When first hatched, fish do not school with one another. They are much more likely to swim alone, thus making themselves easier targets for predators. As they get older, however, they find other fish with which to swim. Usually they'll start out swimming with just a few other fish. They'll continue increasing the size of their group until they become recognizable schools.
-
Spawning
-
Many fish will school when it comes time to spawn. A giant group of the fish will congregate; the females will lay their eggs, and the males will release their sperm, all in the same close vicinity. This means that in a very small amount of space there's a vast number of fertilized eggs. This goes back to the fishes' "safety in numbers" technique: A predator might eat some of the eggs, but it can't eat them all.
Eyesight
-
Fish can use their eyesight to assist in schooling. Fishes' eyes are located on either side of the head, which means that while they can't really see forward, they can certainly see the fish on each side of them. This enables them to move well with the school since they can see which direction the fish around them are moving in.
Lateral Lines
-
Many fish have two lines of sensitive cells running along either sides of their bodies. The fish can use these "lateral lines" to sense the movement and location of the fish around them. They can even use them to locate nearby prey. If these lateral lines are somehow damaged and the fish can't see, it will no longer school.
-
References
- Photo Credit Many Fishes image by Rick Chesler from Fotolia.com
