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Gregory R. Mann, Ph.D. {ret.}

Blacktip Reef Shark

“Carcharhinus melanopterus”

Blacktip Reef Sharks are small sharks measuring up to 1.8 meters with short, bluntly rounded snouts, oval eyes and narrow-cusped teeth. They have 2 dorsal fins and no inter-dorsal ridges. Juveniles (70 centimeters) 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 kilograms; frequents depth ranges from the surface to 75 meters. This species is commonly found in shallow waters on or near coral reefs and occasionally in brackish waters. Juveniles are typically found in extremely shallow water (15 to 100 centimeters) inside lagoons, often swimming along the shoreline; adults typically occur on shallow parts of the fore-reef, often moving over the reef crest and onto the reef flat at flood tide. Blacktip Reef Sharks inhabit a relatively small home range and appear to reside close to their home reef but occasionally cross deep-water channels between adjacent reefs.

They are also found in mangrove areas, moving in and out with the tide and even in freshwater near the sea. They occur singly or in small groups. Adults often aggregate in reef channels at low tide. They are found in the Indo-Pacific from the Red Sea and East Africa to the Hawaiian Islands and the Tuamotu Archipelago. They are also found in the eastern Mediterranean through the Suez Canal. Blacktip Reef Sharks are fast, pursuit predators that prefer reef fishes but also feeds on stingrays, crabs, mantis shrimps, crustaceans, cephalopods & mollusks. In the Maldives, this species has been documented feeding cooperatively on small schooling fishes, herding them against the shore and feeding en masse.  This shark also feeds heavily on sea snakes in northern Australia.

A large individual (1.6 meters) was observed attacking a Green Sea Turtle in North Male’ Atoll, Maldives. 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 centimeters. Males mature at about 8 years of age and 95-105 centimeters in length; females mature at about 9 years old and a length of 93-1.4 centimeters. Courtship features the 1 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 & western Pacific Ocean, but 2 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 & large groupers. The is a socially complex species that performs a variety of group behaviors.

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