These sharks are one of the few species in which a specific threat display has been observed. When the shark is agitated, it will swim infigure-8 loops with its pectoral fins pointing downward, its snout pointingupward, and its back arched in a “hunch”. If it continues to be antagonized after displaying this threat behavior, it will likely charge and attack.
The grey reef shark is not typically aggressive, though it should be treated with caution and respect as it has the potential to cause injury if provoked. They may attack spearfishermen, drawn to the movements andsignals sent out by the distressed fish, and any diver that witnesses a threat display should retreat immediately.
These sharks are quite social and are not territorial, often gathering in large, loose groups. They feed mainly on fish, cephalopods (octopi and squid) and crustaceans (crabs and lobsters).