Big-eye scad are unwitting performance artists. To avoid predators, tens of thousands of these silvery fish—also called akule—move in unison in the form of quivering clouds, like the one pictured here. When a predator strikes, the akule formation shape-shifts, confusing the assailant. See the faint forms in the upper-right corner? They’re ulua, and they eat scad. “That may be, of all my photos, the most compacted, dense school I’ve ever seen,” says photographer , who has seen many of these spectacular shows. His book (Bess Press) features the image and dozens more mesmerizing shots. See more of them , and read the rest of this article .