Are small fish actually safer from predators in a dense school rather than spread out?

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It seems to me that if they spread out from each other, so a predator could only eat one in every bite, any single fish is safer because it’s less likely to be that single one, whereas if they’re huddled together and the predator can gobble ten at a time, the likelihood for any single fish being eaten in a bite is 10x higher.

I understand if the optics of a school are designed to look big and maybe scare off predators, but it’s always been phrased to me as if the “game theory” for a single fish makes it safer to pack in with others.

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Anonymous 0 Comments

The fish are all shiny and they camouflage against the school so that you can’t tell where they are.

Imagine trying to find one solitary zebra out in the open. Pretty easy, right? Now imagine trying to single out one zebra in a herd. You can’t, because all the stripes blend together and obscure the outline of any individual. A lion can’t kill or eat a whole herd, it’s looking for one zebra to single out.

So it’s a good defense against any predator that is about the right size to eat one fish. It’s less good against a predator that could eat half a school. But you have to play the percentages. A lot of marine predation is a slightly larger fish eating a slightly smaller fish.

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