The Gray Reef Shark (Carcharhinus amblyrhynchos) is one of the most common sharks found around coral reefs of Indo-Pacific waters.
As its name suggests, the shark is gray overall, with a white underside. The tips of most fins, except the first dorsal fin, are darker, and the trailing edge of the caudal fin has a prominent black margin. Some individuals have a white pattern on the leading edge of the dorsal fin. It has been recorded at up to 255 cm. The Blacktip Reef Shark looks similar, and also common, but is distinguished by a black tip on the first dorsal fin.
They are active during the day, but more so at night, feeding on reef fishes, squids, octopus, and various crustaceans such as crabs and shrimp.
Reproduction is viviparous, with 1-6 pups in a litter.
This species is social, aggregating in favored areas, often near dropoffs at the edge of a reef, or in atoll passes where there is a strong current. They are often curious, will investigate human scuba divers, and have been implicated in attacks, although there is some debate as to whether the sharks are fundamentally aggressive or have simply reacted badly to perceived threats by divers. They have been observed to adopt a distinctive "hunching" posture when feeling threatened, the body bent into a sort of "S" shape.
The numbers of Gray Reef Sharks have declined in recent years.
- FishBase info for gray reef shark (http://www.fishbase.org/Summary/SpeciesSummary.cfm?genusname=Carcharhinus&speciesname=amblyrhynchos)
- Elasmo Research page on agonistic behavior (http://www.elasmo-research.org/education/topics/b_agonism.htm)