Animal Behavior

Animal collective behavior [blank] itself in often-mesmerizing visual displays of swarming insects, flocks of birds in flight, and schools of fish pulsating underwater as a single unit. Now, researchers report they've found a possible reason for a [blank] display of collective behavior from fish shoals in sulphur springs in Mexico: deterring predators. Behavioral ecologist Juliane Lukas explains to The Scientist that sulfur mollies gather in large shoals at the surface of the low-oxygen springs to avoid hypoxia. There, they're [blank] for the picking by predators such as kingfishers, kiskadees, and other birds. When presented with a threatening stimulus, these 'carpets of fish', as Lukas describes them, repeatedly [blank] the water in a wave-like fashion by diving down for a few seconds, triggering their neighbors to mimic their diving behavior. Lukas and her colleagues decided to investigate why.