Triaenodon obesus, Whitetip Reef Shark [+]
Kingdom Animalia
Phylum Chordata
Class Elasmobranchii
Order Carcharhiniformes
Family Carcharhinidae
Genus Triaenodon
species: Triaenodon obesus [+ITIS +WoRMS]
|
← Previous Photo | Next Photo → |
Description & Behavior
Video: Whitetip Reef sharks of the Galápagos and Red Sea (1:16 | 4.4MB)
The whitetip reef shark, Trianodon obesus (Rüppell, 1837), is a slender species with a short, blunt snout. It is brown-gray on the dorsal side, white on the ventral side. There are scattered dark gray spots along the sides of the body.
The tips of the first dorsal fin and upper caudal fin lobe are brilliant white. The tip of the second dorsal fin and lower caudal fin lobe are also white in some animals. Spiracles usually present, teeth tricuspidate (three-pronged, with a smaller secondary cusp on either side of the central blade), numbering 47-50/44-46, in at least 2 functional rows.
This species is reported to grow to 2.3 m in length but adults over 1.6 m long are rarely seen. Max. published weight: 18 kg; max. reported age: 25 years.
World Range & Habitat
The whitetip reef shark is found in tropical marine waters, most abundant on the fore-reef and during daylight hours is often associated with coral reefs or lying on the bottom in caves and under ledges. Individuals often return to favored resting sites at the same times each day, often for several years. Highly social, these sharks often lie together in groups on the bottom, stretched out side-by-side and even stacked like chord wood. Home ranges of individuals are very small, typically only 0.5 km² or so.
In Australia it is recorded from northwestern Australia, around the tropical north and south to the Queensland coast. It is one of the most abundant species found near coral reefs, together with blacktip reef shark, Carcharhinus melanopterus, and gray reef shark, C. amblyrhynchos. Prefers shallow water, but has been found down to 330 m. This shark lives near the bottom or in caves and crevices. Compared to typical reef sharks (requiem sharks), this species swims in a more undulating manner. Primarily nocturnal, but seems to be correlated with tidal ranges. They can be found in the same area for months (a few square kilometers) but territoriality is not known. Sluggish inhabitant of lagoons and seaward reefs where it is often found resting in caves or under coral ledges during the day, or usually on a sand patch, or in a channel. More active at night or during slack tide in areas of strong currents. Travels distances from about 0.3-3 km in periods up to about 1 year.
Feeding Behavior (Ecology)
The whitetip reef shark feeds nocturnally on benthic animals such as fishes, octopuses, spiny lobsters, and crabs. Observed feeding cooperatively at night at Cocos Island, Costa Rica, moving over the reef face like a phalanx of soldiers, flushing out sleeping prey. Foraging individuals often pause to wriggle their elongate bodies into crevices and under coral heads, twisting and turning violently and often breaking off coral and tearing their fins and skin. As such, the whitetip reef shark occupies a niche more like that of a moray eel than a typical shark.
Life History
One to five 60 cm young per litter. Mode: dioecism. Fertilization: internal (oviduct). Reproductive guild: internal live bearers. Description of life cycle and mating behavior: Viviparous, with 1-5 young per litter. Gestation is about 12 months. Size at birth 52-60 cm total length. Distinct pairing with embrace. One to 11 males follow a female until one gently nips her gill region; if she accepts him, he grasps one of her pectoral fins in his mouth and mates with her, their heads close together on the bottom and their bodies entwined and extending up into the water column at an angle of about 45 degrees. Mating typically lasts 1.5 to 3 minutes. They reach sexual maturity at an age of about 8 years and a length of about 1 m (males and females). Size at birth 52-60 cm total length.
Conservation Status/Additional Comments
The whitetip reef shark is a curious species that often approaches divers. It is not considered dangerous to humans. Its restricted habitat, depth range, small litter size and moderately late age at maturity suggest that, with increasing fishing pressure, this species may become threatened.
Rarely reported to attack humans, but is potentially dangerous, particularly when when fish have been speared. Probably fished wherever it occurs (no data). Meat and liver utilized fresh for human consumption. The liver of this shark has been reported as toxic.
References & Further Research
BioOne ~ CITES ~ Discover Life ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList ~ MarineBio Network ~ NCBI ~ SCIRIS ~ SIRIS ~ Tree of Life Web Project ~ Wikipedia
Whitetip reef shark (Triaenodon obesus) - Shark Foundation
Whitetip Reef Shark - Triaenodon obesus - Florida Museum of Natural History
Search the Web for Whitetip Reef Shark » ARKive ~ Ask.com ~ Ask Jeeves ~ bing ~ deviantART ~ dmoz ~ Dogpile ~ Google Images ~ MySpace Images ~ OceanFootage ~ Picsearch ~ StumbleUpon ~ Yahoo! Images ~ YouTube
