Chevron barracuda

Photo: Mark Rosenstein · CC BY-NC

Chevron barracuda form the classic cylindrical baitball schools seen on healthy outer reefs throughout the Indo-Pacific, with schools sometimes numbering thousands of individuals that rotate in a tight, mesmerising vortex around a central axis. The school behaviour is a defence mechanism: the synchronized movement and reflection off silver scales confuses predators attempting to single out an individual. At Dodola, barracuda schools form at the current-swept point of the outer reef and can be approached to within a few metres, as the fish are inquisitive and hold position rather than fleeing.