On the infrequent occasions when they swim in oceanic waters, grey reef sharks often associate with marine mammals or large pelagic fishes, such as sailfish (Istiophorus platypterus). There is an account of around 25 grey reef sharks following a large pod of bottlenose dolphins (Tursiops sp.), along with 25 silky sharks (C. falciformis) and a single silvertip shark. Rainbow runners (Elagatis bipinnulata) have been observed rubbing against grey reef sharks, using the sharks' rough skin to scrape off parasites.
The Caribbean Reef Shark is known to be relatively passive and typically doesn’t pose much of a threat to scuba divers, snorklers, swimmers, or other humans it comes into contact with. They actually tend to avoid human interaction entirely. As per theInternational Shark Attack Files, there have been 27 attacks documented since 1960, of which none have been fatal. Of those attacks, it’s believe that 4 of them were caused because the shark mistakenly thought the person was a food source. The rest of the attacks were provoked attacks such as sharks caught in fishing equipment biting the fisherman.
A reef is a bar of rock, sand, coral or similar material, lying beneath the surface of water. Many reefs result from abiotic processes (i.e. deposition of sand, wave erosion planing down rock outcrops, and other natural processes), but the best known reefs are the coral reefs of tropical waters developed through biotic processes dominated by corals and coralline algae.