Grey reef sharks were the first shark species known to perform a threat display, a stereotypical behavior warning that it is prepared to attack. 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.
The Caribbean reef shark infrequently attacks humans. In general, a shark attack on a human is behaviorally similar to an attack upon natural prey. A human is more susceptible to being attacked if the shark is cornered and feels that there is no escape route. In situations like these, the shark may rake the victim during the attack resulting in lacerations.
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.
In California, Reef Check helps ensure the long-term sustainability and health of the nearshore rocky reefs and kelp forests. Reef Check California volunteers are divers, fishermen, kayakers, surfers, boaters, and a wide range of Californians who take a proactive role in making sure that our nearshore ecosystems are healthy and well managed. We monitor rocky reefs inside and outside of California's marine protected areas (MPAs). We work with marine managers, researchers and the public to provide the scientific data needed to make informed, science-based decisions for the sustainable management and conservation of California's ocean environment. We would love your support, volunteer today!
Caribbean reef sharks are sometimes seen resting motionless on the sea floor or inside caves; it is the first active shark species in which such a behavior was reported. In 1975, Eugenie Clark investigated the famed "sleeping sharks" inside the caves at Isla Mujeres off the Yucatan Peninsula, and determined that the sharks were not actually asleep as their eyes would follow divers. Clark speculated that freshwater upwellings inside the caves might loosen parasites on the sharks and produce an enjoyable "narcotic" effect. If threatened, Caribbean reef sharks sometimes perform a threat display, in which they swim in a short, jerky fashion with frequent changes in direction and repeated, brief (1–1.2 second duration) drops of the pectoral fins. This display is less pronounced than the better-known display of the grey reef shark (C. amblyrhynchos).
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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. 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. The average litter size is four to six, with a gestation period of one year. Females become pregnant every other year. 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).
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.
This species is taken by commercial and artisanal longline and gillnet fisheries throughout its range. It is valued for meat, leather, liver oil and fishmeal. The Caribbean reef shark is the most common shark landed in Colombia (accounting for 39% of the longline catch by occurrence), where it is utilized for its fins, oil and jaws (sold for ornamental purposes). In Belize, this species is mainly caught as bycatch on hook-and-line intended for groupers and snappers; the fins are sold to the lucrative Asian market and the meat sold in Belize, Mexico, and Guatemala to make "panades", a tortilla-like confection. A dedicated shark fishery operated in Belize from the mid-1900s to the early 1990s, until catches of all species saw dramatic declines. The flesh of this species may contain high levels of methylmercury and other heavy metals.
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.
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.