Blacktip reef sharks are viviparous with a yolk-sac placenta, with a gestation period about 10 months and litter size of 2-4 pups. Size at birth ranges from 33-52 cm. Males mature at about eight years of age and 95-105 cm in length; females mature at about 9 years old and a length of 93-110 cm. Courtship features the one or more males following closely behind a female. Reproductive behavior includes distinct pairing with embrace where the male grasps the female’s pectoral fin between his teeth and mates belly to belly. There is one breeding season in the central and western Pacific, but two seasons in the Indian Ocean. Females rest for 8-14 month between pregnancies to rebuild their energy stores. Blacktip reef sharks are preyed upon by other sharks and large groupers. The is a socially complex species that performs a variety of group behaviors.
The "hunch" threat display of the grey reef shark is the most pronounced and well-known agonistic display (a display directed towards competitors or threats) of any shark. Investigations of this behavior have been focused on the reaction of sharks to approaching divers, some of which have culminated in attacks. The display consists of the shark raising its snout, dropping its pectoral fins, arching its back, and curving its body laterally. While holding this posture, the shark swims with a stiff, exaggerated side-to-side motion, sometimes combined with rolls or figure-8 loops. The intensity of the display increases if the shark is more closely approached or if obstacles are blocking its escape routes, such as landmarks or other sharks. If the diver persists, the shark will either retreat or launch a rapid open-mouthed attack, slashing with its upper teeth.[3]

The grey reef shark (Carcharhinus amblyrhynchos, sometimes misspelled amblyrhynchus or amblyrhinchos)[2] is a species of requiem shark, in the family Carcharhinidae. One of the most common reef sharks in the Indo-Pacific, it is found as far east as Easter Island and as far west as South Africa. This species is most often seen in shallow water near the drop-offs of coral reefs. The grey reef shark has the typical "reef shark" shape, with a broad, round snout and large eyes. This species can be distinguished from similar species by the plain or white-tipped first dorsal fin, the dark tips on the other fins, the broad, black rear margin on the tail fin, and the lack of a ridge between the dorsal fins. Most individuals are less than 1.9 m (6.2 ft) long.
One useful definition distinguishes reefs from mounds as follows: Both are considered to be varieties of organosedimentary buildups – sedimentary features, built by the interaction of organisms and their environment, that have synoptic relief and whose biotic composition differs from that found on and beneath the surrounding sea floor. Reefs are held up by a macroscopic skeletal framework. Coral reefs are an excellent example of this kind. Corals and calcareous algae grow on top of one another and form a three-dimensional framework that is modified in various ways by other organisms and inorganic processes. By contrast, mounds lack a macroscopic skeletal framework (see stromatolite). Mounds are built by microorganisms or by organisms that don't grow a skeletal framework. A microbial mound might be built exclusively or primarily by cyanobacteria. Excellent examples of biostromes formed by cyanobacteria occur in the Great Salt Lake in Utah, and in Shark Bay on the coast of Western Australia.

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.
Along with the blacktip reef shark (C. melanopterus) and the whitetip reef shark (Triaenodon obesus), the grey reef shark is one of the three most common sharks inhabiting Indo-Pacific reefs. They actively expel most other shark species from favored habitats, even species larger in size.[3] In areas where this species co-exists with the blacktip reef shark, the latter species occupies the shallow flats, while the former stays in deeper water.[4] Areas with a high abundance of grey reef sharks tend to contain few sandbar sharks (C. plumbeus), and vice versa; this may be due to their similar diets causing competitive exclusion.[11]
A heavy-bodied shark with a "typical" streamlined shape, the Caribbean reef shark is difficult to distinguish from other large requiem shark species. It usually measures 2–2.5 m (6.6–8.2 ft) long; the maximum recorded length is 3 m (9.8 ft) and the maximum reported weight is 70 kg (150 lb).[5][6] The coloration is dark gray or gray-brown above and white or white-yellow below, with an inconspicuous white band on the flanks. The fins are not prominently marked, and the undersides of the paired fins, the anal fin, and the lower lobe of the caudal fin are dusky.[2][4]

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]
My home in the coral reefs is being damaged by ocean acidification—which occurs when the ocean absorbs carbon and becomes acidified. I love living among thriving reefs, but increasing acidification degrades the physical structure of these reefs, putting my habitat and food supply at risk. This affects all the creatures living among the reef—not just my team of fellow blacktip reef sharks.
The "hunch" threat display of the grey reef shark is the most pronounced and well-known agonistic display (a display directed towards competitors or threats) of any shark. Investigations of this behavior have been focused on the reaction of sharks to approaching divers, some of which have culminated in attacks. The display consists of the shark raising its snout, dropping its pectoral fins, arching its back, and curving its body laterally. While holding this posture, the shark swims with a stiff, exaggerated side-to-side motion, sometimes combined with rolls or figure-8 loops. The intensity of the display increases if the shark is more closely approached or if obstacles are blocking its escape routes, such as landmarks or other sharks. If the diver persists, the shark will either retreat or launch a rapid open-mouthed attack, slashing with its upper teeth.[3]
Juvenile Caribbean reef sharks are preyed upon by larger sharks such as the tiger shark (Galeocerdo cuvier) and the bull shark (C. leucas). Few parasites are known for this species; one is a dark variegated leech often seen trailing from its first dorsal fin.[4] Off northern Brazil, juveniles seek out cleaning stations occupied by yellownose gobies (Elacatinus randalli), which clean the sharks of parasites while they lie still on the bottom.[10] Horse-eye jacks (Caranx latus) and bar jacks (Carangoides ruber) routinely school around Caribbean reef sharks.[11]
Founded in 1996, the Reef Check Foundation exists to help preserve the oceans and reefs which are critical to our survival, yet are being destroyed. With headquarters in Los Angeles and volunteer teams in more than 90 countries and territories, Reef Check works to protect tropical coral reefs and California rocky reefs through education, research and conservation.
Typically a solitary animal, juvenile blacktip reef sharks will commonly conjugate in shallow regions during high tide. Vulnerable to larger predators, they will reside in shallower areas until larger in size. Blacktip reef sharks tend to be more active during dawn and dusk, but like most sharks they are opportunistic feeders. Their diet consists of crustaceans, squid, octopus, and bony fish.
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.

A heavy-bodied shark with a "typical" streamlined shape, the Caribbean reef shark is difficult to distinguish from other large requiem shark species. It usually measures 2–2.5 m (6.6–8.2 ft) long; the maximum recorded length is 3 m (9.8 ft) and the maximum reported weight is 70 kg (150 lb).[5][6] The coloration is dark gray or gray-brown above and white or white-yellow below, with an inconspicuous white band on the flanks. The fins are not prominently marked, and the undersides of the paired fins, the anal fin, and the lower lobe of the caudal fin are dusky.[2][4]
Reproduction is viviparous; once the developing embryos exhaust their supply of yolk, the yolk sac develops into a placental connection through which they receive nourishment from their mother. Mating is apparently an aggressive affair, as females are often found with biting scars and wounds on their sides.[4] At the Fernando de Noronha Archipelago and Atol das Rocas off Brazil, parturition takes place at the end of the dry season from February to April, while at other locations in the Southern Hemisphere, females give birth during the Amazon summer in November and December.[4][12] The average litter size is four to six, with a gestation period of one year. Females become pregnant every other year.[8] The newborns measure no more than 74 cm (29 in) long; males mature sexually at 1.5–1.7 m (59–67 in) long and females at 2–3 m (79–118 in).[4]

Grey reef sharks were the first shark species known to perform a threat display, a stereotypical behavior warning that it is prepared to attack.[3] The display involves a "hunched" posture with characteristically dropped pectoral fins, and an exaggerated, side-to-side swimming motion. Grey reef sharks often do so if they are followed or cornered by divers to indicate they perceive a threat. This species has been responsible for a number of attacks on humans, so should be treated with caution, especially if they begin to display. They are caught in many fisheries and are susceptible to local population depletion due to their low reproduction rate and limited dispersal. As a result, the International Union for Conservation of Nature has assessed this species as Near Threatened.
Blacktip reef sharks are viviparous with a yolk-sac placenta, with a gestation period about 10 months and litter size of 2-4 pups. Size at birth ranges from 33-52 cm. Males mature at about eight years of age and 95-105 cm in length; females mature at about 9 years old and a length of 93-110 cm. Courtship features the one or more males following closely behind a female. Reproductive behavior includes distinct pairing with embrace where the male grasps the female’s pectoral fin between his teeth and mates belly to belly. There is one breeding season in the central and western Pacific, but two seasons in the Indian Ocean. Females rest for 8-14 month between pregnancies to rebuild their energy stores. Blacktip reef sharks are preyed upon by other sharks and large groupers. The is a socially complex species that performs a variety of group behaviors.

Reef’s® 30-year heritage was born out of an idea by Fernando and Santiago Aguerre, entrepreneur brothers from South America with a love of surf and beach culture, to create a high-quality active lifestyle sandal. To bring their vision to life, the brothers moved to Southern California to manage the Reef brand, and they set up production in Sao Paulo Brazil in 1984, where they first produced the iconic sandal that made Reef the leader in open-toe footwear. 

The "hunch" threat display of the grey reef shark is the most pronounced and well-known agonistic display (a display directed towards competitors or threats) of any shark. Investigations of this behavior have been focused on the reaction of sharks to approaching divers, some of which have culminated in attacks. The display consists of the shark raising its snout, dropping its pectoral fins, arching its back, and curving its body laterally. While holding this posture, the shark swims with a stiff, exaggerated side-to-side motion, sometimes combined with rolls or figure-8 loops. The intensity of the display increases if the shark is more closely approached or if obstacles are blocking its escape routes, such as landmarks or other sharks. If the diver persists, the shark will either retreat or launch a rapid open-mouthed attack, slashing with its upper teeth.[3]
Tax-deductible donations made to Tetiaroa Society help fund critical conservation efforts, scientific research being conducted at our Ecostation, and education programs for the local schools. Your contribution also helps us advance what we are doing on Tetiaroa as a model for island/earth sustainability. We deeply appreciate your generosity and look forward to sharing our progress with you.
The Reef story started 25 years ago when two brothers from Argentina Fernando and Santiago Aguerre acted on an idea to produce high quality, comfortable yet stylish sandals. Inspired by their love of the California lifestyle and surfing culture, the brothers moved to California in the early 80's and found Reef sandals. With a tiny amount of start up capital of $4000 and after lots of hard work Reef is now widely considered to be the number one sandal brand in the world.
Grey reef sharks are prey for larger sharks, such as the silvertip shark.[9] At Rangiroa Atoll in French Polynesia, great hammerheads (Sphyrna mokarran) feed opportunistically on grey reef sharks that are exhausted from pursuing mates.[15] Known parasites of this species include the nematode Huffmanela lata and several copepod species that attach to the sharks' skin,[16][17] and juvenile stages of the isopods Gnathia trimaculata and G. grandilaris that attach to the gill filaments and septa (the dividers between each gill).[18][19]
Grey reef sharks were the first shark species known to perform a threat display, a stereotypical behavior warning that it is prepared to attack.[3] The display involves a "hunched" posture with characteristically dropped pectoral fins, and an exaggerated, side-to-side swimming motion. Grey reef sharks often do so if they are followed or cornered by divers to indicate they perceive a threat. This species has been responsible for a number of attacks on humans, so should be treated with caution, especially if they begin to display. They are caught in many fisheries and are susceptible to local population depletion due to their low reproduction rate and limited dispersal. As a result, the International Union for Conservation of Nature has assessed this species as Near Threatened.
But another potential cause is that these sharks are skittish around people. So when too many people move into the area, the reef sharks flee to other coral reefs. Indeed, the researchers found far more sharks at small, isolated reefs than they expected. But this in itself is a danger to the reef sharks. With so many sharks concentrated in a small area, “if you really wanted to, you could fish out a few hundred sharks very easily,” said Friedlander.

Based on morphological similarities, Jack Garrick in 1982 grouped this species with the bignose shark (C. altimus) and the sandbar shark (C. plumbeus), while Leonard Compagno in 1988 placed it as the sister species of the grey reef shark (C. amblyrhynchos). A phylogenetic analysis based on allozyme data, published by Gavin Naylor in 1992, indicated that the Caribbean reef shark is the sister taxon to a clade formed by the Galapagos shark (C. galapagensis), dusky shark (C. obscurus), oceanic whitetip shark (C. longimanus), and the blue shark (Prionace glauca). However, more work is required to fully resolve the interrelationships within Carcharhinus.[3]

Are there so few reef sharks because of human activities such as fishing and finning, or were there never very many to start with? To answer this question, a team of marine biologists (which did not include Friedlander) decided to count reef sharks at coral reefs close and far to human settlements to better understand how humans impact their populations.
Grey reef sharks are active at all times of the day, with activity levels peaking at night.[4] At Rangiroa, groups of around 30 sharks spend the day together in a small part of their collective home range, dispersing at night into shallower water to forage for food. Their home range is about 0.8 km2 (0.31 sq mi).[25] At Enewetak in the Marshall Islands, grey reef sharks from different parts of the reef exhibit different social and ranging behaviors. Sharks on the outer ocean reefs tend to be nomadic, swimming long distances along the reef, while those around lagoon reefs and underwater pinnacles stay within defined daytime and night-time home ranges.[26] Where there are strong tidal currents, grey reef sharks move against the water: towards the shore with the ebbing tide and back out to sea with the rising tide. This may allow them to better detect the scent of their prey, or afford them the cover of turbid water in which to hunt.[25]
Despite its abundance in certain areas, the Caribbean reef shark is one of the least-studied large requiem sharks. They are believed to play a major role in shaping Caribbean reef communities. These sharks are more active at night, with no evidence of seasonal changes in activity or migration. Juveniles tend to remain in a localized area throughout the year, while adults range over a wider area.[7]

Typically a solitary animal, juvenile blacktip reef sharks will commonly conjugate in shallow regions during high tide. Vulnerable to larger predators, they will reside in shallower areas until larger in size. Blacktip reef sharks tend to be more active during dawn and dusk, but like most sharks they are opportunistic feeders. Their diet consists of crustaceans, squid, octopus, and bony fish.
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