Thresher sharks are large lamniform sharks of the family Alopiidae found in all temperate and tropical oceans of the world; the family contains four species, all within the genus Alopias.

The whitetip reef shark (Triaenodon obesus) is a species of requiem shark, in the family Carcharhinidae, and the only member of its genus.
A small shark usually not exceeding 1.6 m (5.2 ft) in length, this
species is easily recognizable by its slender body and short but broad
head, as well as tubular skin flaps beside the nostrils, oval eyes with vertical pupils, and white-tipped dorsal and caudal fins. One of the most common sharks found on Indo-Pacific coral reefs, the whitetip reef shark occurs as far west as South Africa and as far east as Central America. It is typically found on or near the bottom in clear water, at a depth of 8–40 m (26–131 ft).

During the day, whitetip reef sharks spend much of their time
resting inside caves. Unlike other requiem sharks, which rely on ram
ventilation and must constantly swim to breathe, this shark can pump
water over its gills and lie still on the bottom. At night, whitetip reef sharks emerge to hunt bony fishes, crustaceans, and octopus
in groups, their elongate bodies allowing them to force their way into
crevices and holes to extract hidden prey. Individuals may stay within a
particular area of the reef for months or years, frequently returning
to the same shelter. This species is viviparous, in which the developing embryos are sustained by a placental connection to their mother. One of the few sharks in which mating
has been observed in the wild, receptive female whitetip reef sharks
are followed by prospective males, which attempt to grasp her pectoral fin and maneuver the two of them into positions suitable for copulation. Females give birth to one to six pups every other year, after a gestation period of 10–13 months.

Whitetip reef sharks are rarely aggressive towards humans, though they may investigate swimmers closely. However, spear fishers are at risk of being bitten by one attempting to steal their catch. This species is caught for food, though ciguatera poisoning resulting from its consumption has been reported. The IUCN has assessed the whitetip reef shark as Near Threatened,
noting its numbers are dwindling due to increasing levels of
unregulated fishing activity across its range. The slow reproductive
rate and limited habitat preferences of this species renders its
populations vulnerable to overfishing.

The whitetip reef shark (Triaenodon obesus) is a species of requiem shark, in the family Carcharhinidae, and the only member of its genus.
A small shark usually not exceeding 1.6 m (5.2 ft) in length, this
species is easily recognizable by its slender body and short but broad
head, as well as tubular skin flaps beside the nostrils, oval eyes with vertical pupils, and white-tipped dorsal and caudal fins. One of the most common sharks found on Indo-Pacific coral reefs, the whitetip reef shark occurs as far west as South Africa and as far east as Central America. It is typically found on or near the bottom in clear water, at a depth of 8–40 m (26–131 ft).

During the day, whitetip reef sharks spend much of their time
resting inside caves. Unlike other requiem sharks, which rely on ram
ventilation and must constantly swim to breathe, this shark can pump
water over its gills and lie still on the bottom. At night, whitetip reef sharks emerge to hunt bony fishes, crustaceans, and octopus
in groups, their elongate bodies allowing them to force their way into
crevices and holes to extract hidden prey. Individuals may stay within a
particular area of the reef for months or years, frequently returning
to the same shelter. This species is viviparous, in which the developing embryos are sustained by a placental connection to their mother. One of the few sharks in which mating
has been observed in the wild, receptive female whitetip reef sharks
are followed by prospective males, which attempt to grasp her pectoral fin and maneuver the two of them into positions suitable for copulation. Females give birth to one to six pups every other year, after a gestation period of 10–13 months.

Whitetip reef sharks are rarely aggressive towards humans, though they may investigate swimmers closely. However, spear fishers are at risk of being bitten by one attempting to steal their catch. This species is caught for food, though ciguatera poisoning resulting from its consumption has been reported. The IUCN has assessed the whitetip reef shark as Near Threatened,
noting its numbers are dwindling due to increasing levels of
unregulated fishing activity across its range. The slow reproductive
rate and limited habitat preferences of this species renders its
populations vulnerable to overfishing.