The Gathering Swarms

As the only creatures on earth to breed in the Antarctic winter, their survival, as well as those of their chicks, is put in jeopardy when the temperature falls to 40 below. So, instinctively, emperor penguins all converge on the same central point and begin to form a huddle. As those on the outside take the brunt of the cold, those on the inside take tiny steps that move the huddle in waves.

In Sonora, Mexico, thousands of Gulf Grunion fish act on a seemingly suicidal desire to breed out of water. The female grunion deposit eggs in the sand as far from aquatic predators as possible. The eggs remain buried in the wet sand and hatch in about 10 days, at which point the young grunion make their way back into the water.

The seasonal movement of billions of sardines along the coast of South Africa, the greatest fish migration on the planet, includes a stunning example of collective thinking to throw off predators. Synchronous movement by the sardines relies on a pressure sense that runs along their bodies to detect the movements of their nearest neighbors.