What is the scientific name and family of the grey reef shark, and what are its common names?

The grey reef shark is scientifically known as *Carcharhinus amblyrhynchos*. It belongs to the family Carcharhinidae, commonly referred to as requiem sharks. Other common names used for this species include black-vee whaler, bronze whaler, Fowler's whaler shark, graceful shark, graceful whaler shark, grey shark, grey whaler shark, longnose blacktail shark, school shark, and shortnose blacktail shark, though some of these names are also applied to other shark species.

What is the geographical distribution of the grey reef shark?

The grey reef shark is found in the Indo-Pacific region. Its range extends as far east as Easter Island and as far west as South Africa. Specifically, in the Indian Ocean, it is found from South Africa to India, including Madagascar, the Red Sea, and the Maldives. In the Pacific Ocean, its range covers Southern China to northern Australia and New Zealand, encompassing areas like the Gulf of Thailand, the Philippines, and Indonesia, as well as numerous Pacific islands.

Describe the typical physical characteristics that distinguish the grey reef shark.

The grey reef shark has a streamlined body with a broad, round snout and large eyes. It can be identified by its first dorsal fin, which is plain or white-tipped, and the dark tips on its other fins. A key feature is the broad, black rear margin on its caudal fin (tail fin). Additionally, there is no ridge between its dorsal fins. Most individuals are less than 1.88 meters (6.2 feet) long.

What is the conservation status of the grey reef shark, and why is it considered endangered?

The grey reef shark is assessed as endangered by the International Union for Conservation of Nature (IUCN). This status is due to its susceptibility to local population depletion caused by its slow reproduction rate, specific habitat requirements, and tendency to remain within limited areas. It is also caught in multispecies fisheries and faces threats from the degradation of its coral reef habitats.

Who first described the grey reef shark, and what was its original scientific classification?

The grey reef shark was first described in 1856 by the Dutch ichthyologist Pieter Bleeker. He initially classified it as *Carcharias (Prionodon) amblyrhynchos* in the scientific journal *Natuurkundig Tijdschrift voor Nederlandsch-Indië*. Later, authors moved the species to the genus *Carcharhinus*.

What is the type specimen for the grey reef shark, and where was it collected?

The type specimen for the grey reef shark was a female measuring 1.5 meters (4.9 feet) in length. This specimen was collected from the Java Sea.

How has the scientific classification of the grey reef shark evolved, particularly regarding the species *C. wheeleri*?

In older scientific literature, the grey reef shark was often referred to as *C. menisorrah*. The blacktail reef shark (*C. wheeleri*), found in the western Indian Ocean, was once considered a distinct species, differentiated by a white tip on its first dorsal fin, a shorter snout, and one fewer upper tooth row. However, most current authors regard *C. wheeleri* as the same species as the grey reef shark.

Based on morphological and genetic analyses, what other shark species is the grey reef shark considered most closely related to?

Based on morphological characteristics, vertebral counts, and tooth shapes, Garrick (1982) concluded that the grey reef shark is most closely related to the silvertip shark (*Carcharhinus albimarginatus*). This interpretation was further supported by a 1992 allozyme phylogenetic analysis conducted by Lavery.

Describe the body shape, snout, and eyes of the grey reef shark.

The grey reef shark possesses a streamlined and moderately stout body. It is characterized by a long, blunt snout and large, round eyes, which are typical features for many shark species adapted to their environment.

What are the dental characteristics of the grey reef shark, including tooth count and morphology?

The grey reef shark typically has 13 or 14 teeth in both its upper and lower jaws. The upper teeth are triangular with slanted cusps, while the lower teeth have narrower, erect cusps. The serrations on the upper teeth are generally larger than those on the lower teeth.

How does the coloration of the grey reef shark vary, and what causes darkening?

The grey reef shark is typically grey on its dorsal side, sometimes exhibiting a bronze sheen, and white on its ventral side. Individuals that spend time in shallow water can darken in color due to a process similar to tanning, likely a response to sun exposure. Distinctive markings include dusky to black tips on the pectoral, pelvic, second dorsal, and anal fins, and a broad, black band on the rear margin of the caudal fin.

What is the maximum recorded size for a grey reef shark?

While most grey reef sharks are less than 1.9 meters (6.2 feet) in length, the maximum reported length for this species is 2.6 meters (8.5 feet). The maximum reported weight is 33.7 kilograms (74 pounds).

How does the grey reef shark interact with other shark species in its environment?

The grey reef shark is an agile predator that actively expels many other shark species from preferred habitats, even those larger than itself. This dominance contributes to its status as one of the most common sharks on Indo-Pacific reefs, alongside the blacktip reef shark and whitetip reef shark. There's also evidence suggesting competitive exclusion with sandbar sharks due to similar diets.

What are the primary dietary components of the grey reef shark?

The grey reef shark's diet primarily consists of bony fishes. Cephalopods, such as squid and octopus, form the second most important part of their diet. Crustaceans, including crabs, lobsters, and shrimps, make up the remainder of their food intake.

Describe the hunting strategies employed by grey reef sharks.

Grey reef sharks hunt individually or in groups, and they are adept at capturing fish swimming in open water. They have been observed pinning schools of fish against the outer walls of coral reefs. Their hunting strategies complement those of whitetip reef sharks, which are better at catching fish hidden within caves and crevices.

What is the reproductive method of the grey reef shark, and how are its young nourished?

Like other requiem sharks, the grey reef shark is viviparous, meaning the mother gives birth to live young. The developing embryos are nourished through a placental connection, which forms after the yolk sac is depleted, sustaining them until birth.

What is the typical litter size and reproductive frequency for female grey reef sharks?

A female grey reef shark typically gives birth to one to four pups, although litters of up to six pups have been recorded in Hawaii. These litters are born approximately every other year. The number of pups born generally increases with the size of the female.

At what age and size do grey reef sharks reach sexual maturity?

Grey reef sharks reach sexual maturity around seven years of age. At this point, males are typically 1.3 to 1.5 meters (4.3 to 4.9 feet) long, and females are 1.2 to 1.4 meters (3.9 to 4.6 feet) long. However, females on the Great Barrier Reef mature later, around 11 years old.

What is the estimated lifespan of a grey reef shark?

The lifespan of a grey reef shark is estimated to be at least 25 years, based on available research.

Describe the daily activity patterns and social behavior of grey reef sharks.

Grey reef sharks are active at all times but show peak activity at night. During the day, they often form groups, particularly near coral reef drop-offs. These groups disperse in the evening as the sharks begin to hunt. Adult females also form groups in shallow, warmer waters, possibly to accelerate growth or protect developing young. While they form groups, they are considered social rather than territorial.

What is the 'threat display' of the grey reef shark, and what does it signify?

The grey reef shark performs a distinctive threat display, known as a 'hunch' display, which is a warning behavior indicating it is prepared to attack. This behavior involves raising its snout, dropping its pectoral fins, arching its back, and swimming with an exaggerated, stiff side-to-side motion. It is primarily directed towards potential threats, such as divers, rather than other sharks.

Under what circumstances might a grey reef shark become aggressive towards humans?

Grey reef sharks can become dangerous in the presence of food and may be more aggressive if encountered in open water compared to on the reef. They may also attack if pursued or cornered. Divers are advised to retreat slowly if a shark begins its threat display, and camera flashes have been known to incite attacks.

What is the documented history of grey reef shark attacks on humans?

As of 2008, the International Shark Attack File recorded seven unprovoked and six provoked attacks attributed to the grey reef shark. None of these documented attacks were fatal, but the species is capable of inflicting significant damage due to its size and powerful bite.

How do grey reef shark populations face depletion despite their abundance in some areas?

Despite being abundant in pristine locations, grey reef shark populations are vulnerable to localized depletion. This is due to their slow reproductive rate, specific habitat needs, and limited dispersal capabilities. They are also targeted by multispecies fisheries for products like shark fin soup and fishmeal.

What evidence suggests significant population declines in grey reef sharks?

Studies have indicated substantial declines in grey reef shark populations. For instance, in the Chagos Archipelago, numbers fell to 14% of 1970s levels by 1996. On the Great Barrier Reef, populations in fishing zones declined by 97% compared to protected areas, with projections suggesting a further drastic fall without conservation measures.

What role do tidal currents play in the behavior of grey reef sharks?

Where strong tidal currents exist, grey reef sharks are observed to move against the water flow, heading towards the shore with the ebbing tide and returning to the sea with the rising tide. This behavior may aid in detecting prey scents or provide cover in turbid water while hunting.

What is the significance of the black band on the caudal fin of the grey reef shark?

The caudal fin (tail fin) of the grey reef shark features a distinctive, broad, black band along its rear margin, which serves as a key identifying characteristic for the species.

How do grey reef sharks differ from blacktip reef sharks in terms of habitat preference?

In areas where both species coexist, the blacktip reef shark typically occupies the shallower reef flats, while the grey reef shark prefers the deeper waters near the reef drop-offs.

What is the function of the grey reef shark's sharp sense of smell?

The grey reef shark possesses an extremely acute sense of smell, capable of detecting very faint concentrations of substances, such as one part of tuna extract in ten billion parts of seawater. This keen sense is crucial for locating prey.

What is the potential impact of human development on grey reef shark populations?

The continuing degradation of coral reefs due to human development poses a significant threat to grey reef shark populations, as these sharks rely heavily on healthy reef ecosystems for survival and habitat.

What conservation strategies are being considered or implemented for the grey reef shark?

One potential conservation avenue for the grey reef shark is ecotourism, as they are suitable for shark-watching activities. Additionally, profitable diving sites featuring these sharks are increasingly being protected in various countries, such as the Maldives, to help preserve their populations.

What is the typical size range of newborn grey reef sharks?

Newborn grey reef sharks measure between 45 to 60 centimeters (18 to 24 inches) in length at birth.

How do grey reef sharks utilize warmer water temperatures during certain aggregations?

Female grey reef sharks sometimes aggregate in shallow waters, where the warmer temperatures may help accelerate their growth or the growth of their unborn young. This behavior is observed in locations like the northwestern Hawaiian Islands and Johnston Atoll.

What is the relationship between grey reef sharks and marine mammals or large pelagic fish when in oceanic waters?

When grey reef sharks venture into oceanic waters, they are often observed associating with marine mammals or large pelagic fish, such as sailfish. This association might be for foraging opportunities or other ecological interactions.

What is the significance of the 'hunched' posture in the grey reef shark's threat display?

The 'hunched' posture, characterized by a raised snout and dropped pectoral fins, is a key component of the grey reef shark's threat display. It is combined with an exaggerated swimming motion to signal aggression and warn off perceived threats.

How do grey reef sharks' hunting behaviors differ between reef environments and oceanic waters?

Within reef environments, grey reef sharks are known to hunt individually or in groups, often pinning schools of fish against reef walls. In oceanic waters, they have been observed following larger marine animals like pods of bottlenose dolphins, suggesting a different foraging strategy in the open sea.

What is the role of the grey reef shark in its reef ecosystem?

As a fast-swimming, agile predator, the grey reef shark plays a significant role in regulating populations of bony fishes and cephalopods within its reef ecosystem. Its aggressive nature allows it to dominate many other shark species, influencing the overall community structure.

Grey Reef Shark Wiki: Oceanic Sentinels: The Grey Reef Shark's Vital Role

Taxonomic Classification

Scientific Hierarchy

The Grey Reef Shark, scientifically designated as Carcharhinus amblyrhynchos, belongs to the order Carcharhiniformes, commonly known as ground sharks or requiem sharks. This classification reflects its evolutionary lineage and shared characteristics with numerous other shark species.

Kingdom

Animalia

Phylum

Chordata

Class

Chondrichthyes (Cartilaginous Fishes)

Order

Carcharhiniformes

Family

Carcharhinidae (Requiem Sharks)

Genus

Carcharhinus

Species

C. amblyrhynchos

Morphological Characteristics

Distinctive Features

The Grey Reef Shark is characterized by a streamlined, moderately robust physique, featuring a notably broad, rounded snout and substantial, round eyes. Its dentition comprises 13 or 14 teeth in both the upper and lower jaws, with the upper teeth being triangular and possessing slanted cusps, while the lower teeth are narrower and erect. A key distinguishing feature is the plain or white-tipped first dorsal fin, contrasted by dusky to black tips on the pectoral, pelvic, second dorsal, and anal fins. The caudal fin exhibits a broad, black posterior margin.

Coloration and Size

Dorsally, the shark presents a grey coloration, occasionally displaying a bronze hue, transitioning to white ventrally. Individuals inhabiting shallow waters may exhibit a darkened pigmentation due to a tanning effect. Typically, Grey Reef Sharks measure less than 1.88 meters (6.2 feet) in length, with the maximum recorded length being 2.6 meters (8.5 feet) and a maximum weight of 33.7 kg (74 lbs).

Distribution and Habitat

Geographic Range

This species is indigenous to the Indian and Pacific Oceans. Its distribution extends from South Africa eastward to Easter Island, and westward across the Indo-Pacific region, encompassing areas such as India, Madagascar, the Red Sea, the Maldives, Southern China, Northern Australia, New Zealand, and numerous Pacific islands including Hawaii.

Preferred Environment

Grey Reef Sharks are predominantly coastal and pelagic species, typically found in depths up to 60 meters (200 feet), although they have been observed at depths as great as 1,000 meters (3,300 feet). They favor the leeward sides of coral reefs with clear waters and complex topography, frequently congregating near reef drop-offs and channels with significant currents. While less common in lagoons, they may occasionally venture into the open ocean.

Behavioral and Ecological Aspects

Diet and Predation

The Grey Reef Shark's diet primarily consists of bony fishes. Cephalopods, such as squid and octopus, constitute the second most significant food source, supplemented by crustaceans like crabs, lobsters, and shrimps. Larger individuals tend to consume a greater proportion of cephalopods. They are adept predators, often hunting individually or in groups, and have been observed herding schools of fish against reef structures. Their acute sense of smell allows them to detect prey from considerable distances.

Social Structure and Activity

These sharks are highly social, often forming groups of five to twenty individuals, particularly during daylight hours near reef drop-offs. They are not territorial but exhibit distinct home ranges. Activity peaks at night, though they are present throughout the day. They demonstrate a unique "hunch" threat display, involving an exaggerated posture and swimming motion, as a warning to perceived threats, which can escalate to an attack if the perceived threat persists.

Reproduction and Lifespan

As viviparous species, Grey Reef Sharks nourish their embryos via a placental connection. Females typically give birth to litters of one to four pups every other year, with gestation periods estimated between 9 to 14 months. Sexual maturity is generally reached around seven years of age. The species has a documented lifespan of at least 25 years, with females on the Great Barrier Reef maturing later than those in other regions.

Conservation Status and Threats

Endangered Status

The International Union for Conservation of Nature (IUCN) has classified the Grey Reef Shark as Endangered. This designation reflects significant population declines observed in various parts of its range, attributed to a combination of factors including overfishing and habitat degradation.

Threats and Population Declines

Grey Reef Sharks are susceptible to localized depletion due to their slow reproductive rate and specific habitat requirements. They are frequently caught in multispecies fisheries, utilized for products such as shark fin soup and fishmeal. Studies have documented severe population reductions, with some areas showing declines of over 97% in fishing zones compared to protected areas, highlighting the impact of both legal and illegal fishing activities. The ongoing degradation of coral reef ecosystems further exacerbates these threats.

Conservation Strategies

Potential conservation avenues include the development of ecotourism initiatives, as Grey Reef Sharks are suitable for shark-watching activities. The implementation of protected marine areas and stricter fishing regulations are crucial for the recovery and long-term survival of this species.

Human Interactions and Safety

Curiosity and Caution

Grey Reef Sharks are known for their curiosity towards divers and may approach closely. While generally not aggressive unless provoked or in the presence of food, they can become dangerous. Divers are advised to maintain a respectful distance and retreat slowly if the shark exhibits its threat display, as this behavior can precede an attack.

Documented Incidents

Historically, there have been documented instances of Grey Reef Sharks attacking humans, though none have been fatal. These incidents often occur when the sharks are cornered, feel threatened, or are attracted by spearfishing activities. The International Shark Attack File lists several unprovoked and provoked attacks attributed to this species, underscoring the need for caution when encountering them in their natural habitat.

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References

Garrick, J.A.F. (1982). Sharks of the genus Carcharhinus. NOAA Technical Report, NMFS Circ. 445.

Gombessa IV on arte.tv (archive.org)

Robbins, W.D. (2006). Abundance, demography and population structure of the grey reef shark (Carcharhinus amblyrhynchos) and the white tip reef shark (Triaenodon obesus) (Fam. Charcharhinidae). PhD thesis, James Cook University.

Martin, R.A. Coral Reefs: Grey Reef Shark. ReefQuest Centre for Shark Research. Retrieved on April 30, 2009.

A full list of references for this article are available at the Grey reef shark Wikipedia page

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This document has been generated by an Artificial Intelligence, synthesizing information from publicly available academic sources. It is intended for educational and informational purposes at a postgraduate level. While every effort has been made to ensure accuracy and adherence to the provided source material, the content may not be exhaustive or reflect the absolute latest research findings.

This is not professional advice. The information presented herein does not constitute expert consultation in marine biology, conservation science, or ichthyology. Readers are advised to consult primary scientific literature and qualified professionals for definitive information and guidance related to marine ecosystems, species conservation, or any related field.

The creators of this content are not liable for any errors, omissions, or consequences arising from the use of this information.

Oceanic Sentinels

Taxonomic Classification 🏛️

🔬 Scientific Hierarchy

🌳 Kingdom

🌊 Phylum

🐟 Class

🦈 Order

🦈 Family

🦈 Genus

🦈 Species

Morphological Characteristics 📏

🦈 Distinctive Features

🎨 Coloration and Size

Distribution and Habitat 📍

🗺️ Geographic Range

🏝️ Preferred Environment

Behavioral and Ecological Aspects 🧬

🍽️ Diet and Predation

🤝 Social Structure and Activity

👶 Reproduction and Lifespan

Conservation Status and Threats 🌳

⚠️ Endangered Status

🎣 Threats and Population Declines

💡 Conservation Strategies

Human Interactions and Safety 🧑‍🤝‍🧑

👀 Curiosity and Caution

🚨 Documented Incidents

Teacher's Corner 🧑‍🏫

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References

📜 References

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Academic Disclaimer ⚠️

📜 Important Notice

Taxonomic Classification

Scientific Hierarchy

Kingdom

Phylum

Class

Order

Family

Genus

Species

Morphological Characteristics

Distinctive Features

Coloration and Size

Distribution and Habitat

Geographic Range

Preferred Environment

Behavioral and Ecological Aspects

Diet and Predation

Social Structure and Activity

Reproduction and Lifespan

Conservation Status and Threats

Endangered Status

Threats and Population Declines

Conservation Strategies

Human Interactions and Safety

Curiosity and Caution

Documented Incidents

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Academic Disclaimer

Important Notice