The whitetip reef shark (Triaenodon obesus) is one of the most common medium‑sized sharks on Indo‑Pacific coral reefs. It belongs to family Carcharhinidae and the monotypic genus Triaenodon. Famed for its nocturnal, ambush‑style foraging, it rests communally in caves and crevices by day and hunts along reef edges after dusk.
Ecology & Behaviour
Diet: reef teleosts, cephalopods and crustaceans; often probes crevices and patrols reef slopes.
Daily cycle: diurnal resting and nocturnal activity; strong site fidelity with small home ranges.
Reproduction: aplacental viviparous with ~10–13‑month gestation; litters of 1–5 (commonly 2).
Identification
Slender body with a short blunt snout and nasal flaps; relatively small, posteriorly placed first dorsal fin. The first dorsal‑fin tip and upper caudal‑fin tip are conspicuously white. Grey‑brown dorsum, white ventrum; large eyes adapted to low light.
Size & Longevity
Length: commonly 1.2–1.6 m; max ~1.9 m.
Weight: typically 10–20+ kg (regional variation).
Life: about 20–25 years (estimated).
Range & Habitat
Widespread across the tropical/subtropical Indo‑Pacific from the Red Sea/East Africa to the central Pacific islands (e.g., Hawai‘i, Polynesia). Most frequent on reef slopes, ledges and lagoons, commonly at 1–40 m.
Threats & Conservation
Fisheries: targeted/bycatch in handlines, gillnets and longlines; utilized for fins/meat.
Intrinsic vulnerability: late maturity and low fecundity lead to slow recovery.
Habitat degradation: coral bleaching, pollution and tourism disturbance.
IUCN global status: Vulnerable (VU). Priorities: eliminate destructive gears, expand/connect reef MPA networks, set bycatch‑reduction and live‑release protocols, and manage diving/night‑diving to minimize harassment.
