Jack Tamisiea in Scientific American:
Although the jungles of southern Mexico seem like an ideal spot for fieldwork, the region’s sulfur springs are far from a tropical getaway. In addition to the area’s stifling heat, the pools reek of rotten eggs. Their milky, turquoise water is even more inhospitable: it is laced with toxic levels of hydrogen sulfide and contains very little oxygen.
These hellish backwaters, however, serve as the stage for a remarkable display—tens of thousands of fish moving in unison like sports fans doing the wave across a stadium. “It’s mesmerizing—you can stand there literally for hours and just let your mind flow while they do their waves,” says Juliane Lukas, a researcher at Berlin’s Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB). But these pulsating waves are not just captivating. In a study published on December 22 in Current Biology, Lukas and her team identified the pulsating waves as one of the first examples of a collective behavior meant to directly stymie a predator.