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Whitetip Reef Sharks Triaenodon obesus Tyler Grix

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Whitetip Reef Shark around Coral Reefs

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Common Names for Whitetip Reef Sharks around the World English language common names include whitetip reef shark, blunthead shark, blunt-head shark, light-tip shark, reef whitetip, reef whitetip shark, white tip reef shark, white-tip reef shark, whitetip shark, and white-tip shark. Common names in other languages include aileron blanc de lagon (French), arava (Tuamotuan), cazn (Spanish), cazn coralero trompacorta (Spanish), daaha (Somali), endormi requin (French), eno-eno (Gela), faana miyaru (Maldivian), gursh (Arabic), ikan yu (Malay) libaax (Somali), maog (Niuean), malu (Samoan), mamaru (Tahitian), man ll kea (Hawaiian), marracho de covas (Portuguese)

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Where Whitetip Reef Sharks are found in the World

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Geographical Distribution The whitetip reef shark has a wide range in the Pacific Ocean, including South Africa and the Red Sea to Pakistan, Sri Lanka, Burma, Indonesia, Viet Nam, Taiwan, Riu Kiu Islands, Philippines, Australia and New Guinea. It is common in Polynesia, Melanesia, and Micronesia, northward to the Hawaiian Islands, and southwest to the Pitcairns. In the eastern Pacific, the whitetip reef shark lives in waters off the Cocos and Galapagos Islands, and Panama north to Costa Rica. It is one of the most common reef sharks in the Pacific Ocean, along with the blacktip reef shark (Carcharhinus melanopterus) and the grey reef shark (Carcharhinus amblyrhynchos).

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Habitat The whitetip reef shark typically lives along the bottom in clear, shallow waters surrounding coral reefs. It has been reported at depths to 1,083 feet (330 m). Rarely coming to the surface, this shark is capable of lying motionless on the bottom substrate for long periods of time. During daylight hours, whitetip reef sharks form aggregations in caves, sometimes appearing stacked up like a pile of logs. The same sharks often return repeatedly to the same cave for long periods of time, changing location only periodically. The whitetip reef shark is most active throughout the night. Site fidelity is strong with each shark maintaining a small home range for months or years at a time.

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Coloration The whitetip reef shark earns its common name for the distinct white tips on the first dorsal and upper caudal fins. The body is dark gray to brownish, fading to a light ventral surface. Small dark spots may be present over the entire body. The remaining fins may also have white tips, however this may not always hold true.

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Size, Age, and Growth The whitetip reef shark grow to a maximum length of just under 7 feet (2.13 m), however individuals are rare at lengths over 1.6 m (5.25 feet). Males mature at about 3.4 feet (1.05 m) and generally reach 5.5 feet (1.68 m) in length. Females reach maturity at 3.4- 3.57 feet (1.05-1.09 m) and grow to at least 5.18 feet (1.58 m). This species is known to reach a maximum age of at least 25 years.

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Physical Anatomy

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The whitetip reef shark feeds during the night on benthic prey.

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Foods for whitetips sharks. This shark is a specialist in capturing bottom-dwelling prey in caves and crevices, feeding primarily on octopus, lobsters and crabs. It also feeds on bony fishes including eels, squirrelfishes, snappers, damselfishes, parrotfishes, surgeonfishes, and triggerfishes. During the night, this shark becomes very active, searching for prey items along the bottom substrate. When a prey item is located, the shark will pursue it into a crevice and jam itself in after it. The tough skin, slender build, blunt snout, and protective eye ridges make it possible for the whitetip reef shark to hunt successfully within these very small spaces.

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Predators Predators of the whitetip reef shark include large piscivorous fishes such as the tiger shark (Galeocerdo cuvier) and giant grouper (Epinephelus lanceolatus).

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Tiger Shark

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Importance to Humans The whitetip reef shark is fished in the waters off Pakistan, India, Sri Lanka, and Madagascar. Although data on the commercial fishery involving this shark are lacking, it is also probably fished in other waters throughout its range. It is caught with floating and bottom gillnets and longlines. The liver and flesh is marketed for human consumption, although it has been reported to cause ciguatera poisoning.

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Danger to Humans This shark is relatively harmless to humans due to its easygoing disposition and small teeth. It avoids close contact with humans, swimming off when approached by swimmers and divers. Often attracted to food, divers have been able to hand feed individual whitetip reef sharks. However, on occasion, a shark will become overly excited by spearfishing or when bait is present, resulting in a bite to a diver. This species is also known to bite if harassed. In Hawaii, some families regarded this shark as 'aumakua', a guardian spirit. They would feed rather than hunt whitetip reef sharks.

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Conservation The whitetip reef shark is currently listed by the World Conservation Union (IUCN) as "Near Threatened" at this time. The IUCN is a global union of states, governmental agencies, and non- governmental organizations in a partnership that assesses the conservation status of species. Due to restricted habitat and depth range as well as small litter size and late age at maturity, this shark may become threatened with increasing fishing pressure.

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Scientific Article Encountered by divers, very little has been written other than distributional records. The purpose of this paper is to review what is known of the biology of this shark and to present some original data on its life history. These data were assembled incidentally to other projects, as the opportunity arose, beginning December 1966. CLASSIFICATION Carcharias obesus was described by Rtippel1 (1835: 64, pI. 18, fig. 2) from a specimen from Jeddah, Red Sea. The choice of the specific name is unfortunate, for obesus is a slender species. Klausewitz (1960: 291, pI. 42, fig. I, text-fig. 4) illustrated the holotype and its teeth; it is housed at the Senckenberg Museum, Frankfurt, under number 3149. Miller and Henle (1837) proposed the genus Triaenodon, selecting obesus as the type species of the genus. Until recently most authors, including Bigelow and Schroeder (1948), have placed Triaenodon in the Triakidae.

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References http://www.flmnh.ufl.edu/fish/gallery/descript/wtreefshar k/wtreefshark.html http://marinebio.org/species.asp?id=232 http://www.shark.ch/Database/Search/species.html?sh_id =1039 http://www.montereybayaquarium.org/animals/AnimalDet ails.aspx?enc=VsGX+Lst7QaeRUOw1oPluQ

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Resources http://www.flmnh.ufl.edu/fish/gallery/descript/wtreef shark/wtreefshark.html http://marinebio.org/species.asp?id=232 http://www.shark.ch/Database/Search/species.html?s h_id=1039 http://www.montereybayaquarium.org/animals/Anima lDetails.aspx?enc=VsGX+Lst7QaeRUOw1oPluQ

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Whitetip Reef Shark with Scuba Divers

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