As you approach the shiny, moving wall of herring that inhabit the Schooling Exhibit in the Aquarium's Thinking Gallery, you may quickly find that it's pretty difficult to focus on just one fish at a time. In fact, that's exactly the point. Take a look:
It's an effect that can be almost hypnotic to watch. Here's a frozen frame that makes it possible to pick out individual fish:
Groups of schooling fish, like the blueback herring in this exhibit, can coordinate their movements to make themselves look like one big, shimmering blur. This makes it very hard for predators to pick out one particular fish and attempt to chase it down. So, often, all a predator can do is just to swim into the group, mouth open, and hope for the best--not the most effective, or energy-efficient, of tactics.
The adaptations that make schooling behavior possible are very interesting, and almost amount to a special sixth sense for these fish. Check back soon to learn more.