Grey reef shark - Carcharhinus amblyrhynchos
WHAT TO LOOK FOR
A medium-sized to large shark with a moderately long, broadly rounded snout and a black-edged caudal fin.
Gray dorsal surface and a broad black band on the posterior margin of the caudal fin.
Males mature at 4.25 to 4.75 ft [1.3 to 1.45 m], females mature at 4 to 4.5 ft [1.22 to 1.37 m]. Maximum size is 8.3 ft [2.55 m].
The teeth of the upper jaw are narrow-cusped and serrated, those of the lower jaw are awl-shaped.
A coastal-pelagic and inshore species common on coral reefs, often in deeper areas near drop-offs to the open sea, and in shallow lagoons adjacent to areas of strong currents. It is often seen cruising near the bottom but will visit the surface, particularly to investigate food sources. Frequently found on leeward sides of small coral islands.
Indian Ocean, and Western Pacific eastward to Hawaiian Islands.
Prey – Feeds on reef fish less than 12 inches [30 cm] in length, as well as squid, octopus, crabs, lobsters and shrimp.
Reproduction – Viviparous, with yolk-sac placenta. Litter size ranges from 1 to 6 pups following a 12 month gestation period. Size at birth is 18 to 24 inches [45 to 60 cm]. Individuals mature between 7 and 7.5 years, and life-span is thought to be at least 25 years or more.
This is an active, strong-swimming social species that forms daytime aggregations in reef passes and lagoons; at night the groups disperse. Groups of juveniles remain together on pupping grounds.
Gray reef sharks are inquisitive, and in seldom-frequented areas divers have been approached very closely by several of these sharks, particularly when they initially enter the water. However, once the sharks’ curiosity is satisfied they usually retreat and remain at a distance.
Feeding – When feeding stimuli are present the shark may be aggressive and dangerous.
WHAT TO WATCH OUT FOR
This species will perform a threat-display when approached too closely or startled by unusual sounds or quick movements. The display consists of an exaggerated swimming pattern in which the shark wags its head and tail in broad sweeps, arches its back, lifts its head, depresses its pectoral fins and sometimes swims in a horizontal spiral or figure-8 loop in front of its perceived aggressor. The threat may terminate in a high-speed attack.