Blacktail reef shark

📖 Overview

Occurs on continental and insular shelves and oceanic waters adjacent to them . Common on coral reefs, often in deeper areas near drop-offs to the open sea, in atoll passes, and in shallow lagoons adjacent to areas of strong currents . Coastal-pelagic near the bottom, near drop-offs at 1-275 m . Forms daytime schools or aggregations in favored areas . Although active during the day, it is more active nocturnally . Viviparous, with 1-6 pups . Feeds on reef fishes, squids, octopi, crabs, lobsters and shrimps . Tends to be aggressive under baited conditions and readily enters into a frenzy feeding pattern, at which time it may become quite dangerous. Repeatedly incriminated in human attacks. Utilized for human consumption, fishmeal, and other shark products. Minimum depth from Ref. 6871. Maximum length of female taken from Ref. 5213.

🔬 Taxonomy

🐟 Physical Description

Dorsal spines (total): 0; Anal spines: 0. Dark grey or bronze-grey above, white below; caudal fin with a conspicuous wide black posterior margin; undersides of pectoral and pelvic fins with black tips and posterior margins, but fins otherwise not conspicuously black or white-tipped except for white-tipped first dorsal in some individuals .: fusiform / normal.

🌀 Behaviour

Grey reef sharks are active at all times of the day, with activity levels peaking at night. 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 mi2). 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 nighttime home ranges. Where strong tidal currents occur, grey reef sharks move against the water, toward 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. Little evidence of territoriality is seen in the grey reef shark; individuals tolerate others of their species entering and feeding within their home ranges. Off Hawaii, individuals may stay around the same part of the reef up to three years, while at Rangiroa, they regularly shift their locations up to 15 km (9.3 mi). Individual grey reef sharks at Enewetak become highly aggressive at specific locations, suggesting they may exhibit dominant behavior over other sharks in their home areas.

🦐 Diet

Grey reef sharks feed mainly on bony fishes and cephalopods such as squid and octopuses being the second-most important food group, and crustaceans such as crabs, lobsters, and shrimps making up the remainder. The larger sharks take a greater proportion of cephalopods. 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. Hunting groups of up to 700 grey reef sharks have been observed at Fakarava atoll in French Polynesia. 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. Their sense of smell is extremely acute, being capable of detecting one part tuna extract in 10 billion parts of sea water. 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.

🥚 Reproduction

Viviparous, placental . 1-6 pups in a litter . Gestation period about 12 months . Size at birth 50 to 60 cm or 75 cm . Distinct pairing with embrace .

🌍 Habitat & Distribution

Marine; reef-associated; oceanodromous ; depth range 0 - 1000 m , usually 0 - 280 m . Tropical; 29°N - 35°S, 33°E - 151°W West Pacific to Central Pacific: Madagascar and the Mauritius-Seychelles area to Tuamoto Archipelago; north to southern China; south to northern Australia.

🌿 Ecology

📐 Morphometrics

🌡️ Water Parameters & Tolerance

🛡️ Conservation Assessment

📊 Population Risk & Fisheries

🌐 Names & Taxonomy

Scientific Synonyms

🐠 Related Species

🔍 Similar Species

🗺️ Global Occurrence Map

Occurrence records from the Global Biodiversity Information Facility (GBIF) - 12 records indexed .

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