Food, fear and physics help explain group behavior from plankton to whales

The open ocean presents a challenging environment where food is scarce, predators are abundant, and ocean conditions are constantly changing. Animals living in this pelagic zone, which extends from the sunlit surface to the deep sea, must develop unique adaptations to survive. A recent study published in the journal Philosophical Transactions of the Royal Society B: Biological Sciences explores how collective behaviors such as schooling, swarming, vertical migration, and cooperative foraging enable pelagic animals to find food and avoid predators.

Kelly Benoit-Bird, a senior scientist at the Monterey Bay Aquarium Research Institute (MBARI), and William Oestreich, a former NSF postdoctoral fellow now at the University of Zurich, have reviewed these behaviors in their paper. Benoit-Bird heads MBARI's Acoustical Ocean Ecology Team, which employs advanced acoustic technologies to study how animals locate food without becoming prey themselves, and how group behaviors impact predator-prey interactions.

The researchers have discovered that key aspects of the pelagic ocean, including limited and patchy food resources, lack of cover, and the movement of the medium itself, have repeatedly led to the evolution of collective behavior in marine animals, ranging from tiny plankton to massive whales. Examples from various taxa across the ocean depths illustrate how fear, physics, and limited food resources drive the development of group behaviors.

This research provides valuable insights into the evolutionary drivers and adaptive significance of collective behavior in the vast living space of the Earth's oceans.