The small shark is named for its distinct black-tipped fins. Not to be confused with the blacktip shark, a larger species with similar fin coloration, the blacktip reef shark can be found in shallow inshore waters throughout the Indo-Pacific, including coral reefs, reef flats and near drop offs. It may be seen in mangrove areas and even freshwater environments near to shore, moving in and out with the tide. The blacktip reef shark feeds primarily on fish, including many common reef fishes, but will also consume crustaceans, mollusks, and even snakes!
Despite sharks being portrayed as notorious aggressive animals, very few incidents have involved blacktip reef sharks, none being fatal. Still the importance of an apex predator is vital to a balanced and healthy ecosystem. Unfortunately, this species is very susceptible to reef gill netting. And sharks all around continue to be threatened by fishing pressure resulting in a decrease in many shark populations.

WWF works to preserve the coral habitats where reef sharks live through the creation and improved management of marine protected areas, elaboration of fisheries management plans, and the introduction of fishing bans to protect vulnerable species including reef sharks. WWF also promoted the understanding that communities can derive more economic value from reef sharks through tourism than through their capture. We support local communities to set up appropriate ecotourism systems and infrastructure to ensure well-managed and sustainable shark tourism operations.
Grey reef sharks are often curious about divers when they first enter the water and may approach quite closely, though they lose interest on repeat dives.[4] They can become dangerous in the presence of food, and tend to be more aggressive if encountered in open water rather than on the reef.[13] There have been several known attacks on spearfishers, possibly by mistake, when the shark struck at the speared fish close to the diver. This species will also attack if pursued or cornered, and divers should immediately retreat (slowly and always facing the shark) if it begins to perform a threat display.[4] Photographing the display should not be attempted, as the flash from a camera is known to have incited at least one attack.[3] Although of modest size, they are capable of inflicting significant damage: during one study of the threat display, a grey reef shark attacked the researchers' submersible multiple times, leaving tooth marks in the plastic windows and biting off one of the propellers. The shark consistently launched its attacks from a distance of 6 m (20 ft), which it was able to cover in a third of a second.[14] As of 2008, the International Shark Attack File listed seven unprovoked and six provoked attacks (none of them fatal) attributable to this species.[29]
Generally a coastal, shallow-water species, grey reef sharks are mostly found in depths of less than 60 m (200 ft).[11] However, they have been known to dive to 1,000 m (3,300 ft).[2] They are found over continental and insular shelves, preferring the leeward (away from the direction of the current) sides of coral reefs with clear water and rugged topography. They are frequently found near the drop-offs at the outer edges of the reef, particularly near reef channels with strong currents,[12] and less commonly within lagoons. On occasion, this shark may venture several kilometers out into the open ocean.[4][11]
Grey reef sharks feed mainly on bony fishes, with cephalopods such as squid and octopus being the second-most important food group, and crustaceans such as crabs and lobsters making up the remainder. The larger sharks take a greater proportion of cephalopods.[20] These sharks hunt individually or in groups, and have been known to pin schools of fish against the outer walls of coral reefs for feeding.[14] Hunting groups of up to 700 grey reef sharks have been observed at Fakarava atoll in French Polynesia.[21][22] They excel at capturing fish swimming in the open, and they complement hunting whitetip reef sharks, which are more adept at capturing fish inside caves and crevices.[4] Their sense of smell is extremely acute, being capable of detecting one part tuna extract in 10 billion parts of sea water.[13] In the presence of a large quantity of food, grey reef sharks may be roused into a feeding frenzy; in one documented frenzy caused by an underwater explosion that killed several snappers, one of the sharks involved was attacked and consumed by the others.[23]
Despite sharks being portrayed as notorious aggressive animals, very few incidents have involved blacktip reef sharks, none being fatal. Still the importance of an apex predator is vital to a balanced and healthy ecosystem. Unfortunately, this species is very susceptible to reef gill netting. And sharks all around continue to be threatened by fishing pressure resulting in a decrease in many shark populations.

Blacktip reef sharks, Carcharhinus melanopterus (Quoy and Gaimard, 1824), are small sharks measuring up to 1.8 m with short, bluntly-rounded snouts, oval eyes, and narrow-cusped teeth. They have 2 dorsal fins and no interdorsal ridges. Juveniles (< 70 cm) are yellow-brown on their dorsal (upper) sides, white on their ventral (under) sides; adults are brownish-gray and white, respectively. All their fins have conspicuous black or dark brown tips, and posterior (rear) dark edges on their pectoral fins and their upper lobe of their caudal (tail) fins. The prominent black tips of their first dorsal fin contrasts with a light band below it; a conspicuous dark band on their flanks which extends to their pelvic fins. Maximum weight: 24 kg; frequents depth ranges from the surface to 75 m.
Measuring up to 3 m (9.8 ft) long, the Caribbean reef shark is one of the largest apex predators in the reef ecosystem, feeding on a variety of fishes and cephalopods. They have been documented resting motionless on the sea bottom or inside caves, unusual behavior for an active-swimming shark. If threatened, it may perform a threat display in which it frequently changes direction and dips its pectoral fins. Like other requiem sharks, it is viviparous with females giving birth to 4–6 young every other year. Caribbean reef sharks are of some importance to fisheries as a source of meat, leather, liver oil, and fishmeal, but recently they have become more valuable as an ecotourist attraction. In the Bahamas and elsewhere, bait is used to attract them to groups of divers in controversial "shark feedings". This species is responsible for a small number of attacks on humans. The shark attacks usually happen in spring and summer.
Like all sharks, the blacktip reef shark has exceptional sensory systems. From there keen sense of smell to having the ability to see in low light condition, these adaptation have made them prestige at tracking down there prey. Sharks also have an additional sixth sense where they can sense electromagnetic fields in the water. The ampullae of Lorenzini, located in the snout region, enable a shark to detect its prey without physically seeing it.
Cyanobacteria do not have skeletons and individuals are microscopic. Cyanobacteria can encourage the precipitation or accumulation of calcium carbonate to produce distinct sediment bodies in composition that have relief on the seafloor. Cyanobacterial mounds were most abundant before the evolution of shelly macroscopic organisms, but they still exist today (stromatolites are microbial mounds with a laminated internal structure). Bryozoans and crinoids, common contributors to marine sediments during the Mississippian (for example), produced a very different kind of mound. Bryozoans are small and the skeletons of crinoids disintegrate. However, bryozoan and crinoid meadows can persist over time and produce compositionally distinct bodies of sediment with depositional relief.
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