Schooling barracuda

Photo: Malcolm Francis · CC BY-NC

Where great barracuda are solitary, schooling barracuda (typically chevron or blackfin species) form massive, tornado-like aggregations of hundreds to thousands of individuals. Schools form cyclones that divers can enter — fish part around a still diver and close behind, creating an immersive tunnel of silver. The school provides collective predator detection; tightly coordinated movement is a response to perceived threat. Most intense aggregations occur in the morning on exposed reef structures. One of the most reliably spectacular large-school encounters on tropical reefs.