Grey Reef Shark

Photo: Jiro Iguchi · CC BY

Grey reef sharks aggregate around Planet Rock's summit in numbers that reflect Madang's relatively pristine shark populations, circling the current-swept pinnacle in a behavior that combines social interaction with opportunistic hunting. Their threat display — back arching, pectoral fins dropped, exaggerated side-to-side swimming — is the most studied agonistic behavior in any shark species, and understanding its triggers has been fundamental to safe shark-diving practices worldwide.