Giant fish bait ball eclipses scuba divers in Galapagos Islands

Bait balls are a congregation of fish that can number in the millions. Spectacular to see, they form an enormous ball, with the fish tightly packed together for protection from predators. Usually adopted by fish that inhabit open waters, this technique allows individual fish to hide within a group since they cannot hide behind coral or plants as other fish do.

These scuba divers are swimming through the open water around Darwin Island, one of the most iconic and beautiful dive destinations in the world. They swim among schooling hammerhead sharks, sea turtles, and whale sharks as they explore the ocean up to 100 feet from the surface. As they swam, they noticed a sudden decrease in the light, as if they were experiencing an eclipse. Looking above them, they saw that the cause of the darkness was actually this collection of fish. Mesmerized, the group swam under and then around the fish, fascinated by the beauty of such a spectacle.
When fish school like this, they have many eyes and it is nearly impossible for a predator to surprise and ambush them. They react with lightning reflexes to rapidly change directions. Such fluid and coordinated movements appear to be choreographed, although they are not. Schools rapidly disband and then reform as needed. Their silvery bodies dazzle predators and make it difficult for a larger animal to locate and zero in on an individual.

Predators have developed complex hunting techniques in reaction to this schooling behavior, often cooperating between species, or even different species, to attack the bait ball and encourage frenetic and disorganized movements. Fish scramble to remain within the interior of the mass. As fish break from the bait ball and are found on their own, they are more easily targeted and eaten. Occasionally, large fish and whales will charge a bait ball with their mouths open to scoop up a number of fish.