Oceanic Whitetip Shark
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| Oceanic Whitetip Shark Conservation status: Lower risk (nt) | ||||||||||||||||
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| Missing image Oceanic_Whitetip_Shark.jpg Oceanic Whitetip Shark | ||||||||||||||||
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| Carcharhinus longimanus (Poey, 1861) |
The Oceanic Whitetip Shark (Carcharhinus longimanus) is a large pelagic shark of tropical and warm temperate seas. It is named after both its oceanic habitat (living in deep waters), and the white tips on its fins. It is a stocky shark, the most notable features include its rounded fins and the fins' extreme length.
It is an aggressive fish which dominates feeding frenzies, and is said to attack more humans than all other shark species' combined - as such it is a notable danger to ship and plane wrecks. Between its abundance and danger to humans it was a serious concern in the World Wars — a Nova Scotia steamship carrying 1000 was sunk near South Africa by a German submarine — only 192 survived, many deaths are attributed to the Oceanic Whitetip Shark. Some cultures catch it as a delicacy or even for its fin.
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Naming
It was first described by Cuban Felipe Poey in 1861 as Squalus longimanus. The name Pterolamiops longimanus also occupied part of its history. The species name longimanus translates from Latin as "long hands" due to the shape of its pectoral fins. Its other, lesser-used, names include Carcharius obtusus (Garman 1881), Carcharius insularum (Snyder 1904), Pterolamiops magnipinnis (Smith 1958), and Pterolamiops budkeri (Fourmanoir 1961). As well as this variety of scientific names,the Oceanic Whitetip shark also has many common names in the English language: Brown Milbert's sand bar shark, brown shark, nigano shark, and whitetip whaler.
Its non-English common names include apoapo (Samoan), cazón (Spanish), galano (Spanish), galha branca (Portuguese), Hochsee-Weißspitzenhai (German), ikan yu (Malay), köpek baligi (Turkish), marracho (Portuguese), marracho oceánico (Portuguese), marracho-de-pontas-brancas (Portuguese), oceanische witpunthaai (Dutch), opesee-wittiphaai (Afrikaans), parata (Tahitian), patíng (Tagalog), rameur (French), requin à aileron blanc (French), requin blanc (French), requin canal (French), squala alalunga (Italian), tiburon oceanico (Spanish), valkopilkkahai (Finnish), weißspitzenhai (German), yeshalifes (Carolinian), yogore (Japanese), and zarlacz bialopletwy (Polish).
Distribution and habitat
Oceanic_Whitetip_Shark_distribution.png
The Oceanic Whitetip is found worldwide in deep, open water, preferring a temperature greater than 18°C. They are extremely common and widely-distributed, and a map of their habitat appears as a wide band around the world. It may typically be found in equatorial waters; or, specifically, between 20o north and 20o south latitude.
The shark typically dwells in the upper layer of the ocean — from the surface to a depth of 150 metres — though it prefers off-shore deep-ocean areas. According to longline capture data increasing distance from land correlates to a greater population of sharks. It typically lives on its own, though some gatherings are notable where food is available. Unlike many animals it does not operate on a day-and-night basis, but rather swims during both — its swimming style is slow with the pectoral fins widely spread. Despite their decided isolation from others of the same species they may be observed with pilot fishes, dolphin fishes, and remoras. In 1988 Jeremy Stafford-Deitsch reported seeing the species accompanied by a shortfin pilot whale.
Anatomy and appearance
The most distinguishing characteristic of C. longimanus is its long, winglike pectoral fins (hence the specific name longimanus, which is Latin for "long-handed") and Dorsal fin. These fins are noticeably larger than they seem like they should be, although not so large that it may be thought that C. longimanus is a Goblin shark, they're also conspicuously rounded. The shark's nose is rounded also, and its eyes are circular with nictitating membranes.
C. longimanus has a 'typical', although somewhat flattened shark body, often with a mildly humpbacked aspect. It is bronze, brown, bluish, or grey dorsally (the color varies by region), and white ventrally (though it may occasionally have a yellow tint). The teeth of the upper jaw are triangular and serrated, while those in the lower jaw are narrow and somewhat fang-like. Most of the fins on its body (dorsal, pectoral, pelvic, and caudal) have a white tips (very young specimens and the very occasional adult will lack these), from whence the name comes. As well as the white tips a mottling may be noticed on the fins — and even black marks on young specimens. Finally a saddle-like marking may be noted between first and second dorsal fins.
The shark has several kinds of teeth — those in the mandible have a serrated tip and are relatively small and triangular (with a thinner tip). There are between 13 and 15 teeth on either side of the symphysis. The upper jaw teeth are much larger and broader with entirely serrated edges — there are 14 or 15 along each side of the symphysis. The denticles lie flat — they typically have between 5 and 7 ridges.
The maximal size of the Oceanic Whitetip Shark is 4 metres (12 feet), although usually not more than 3 m (9 feet). Its maximal weight is 170 kilograms. The female is larger than the males (though typically only by 10 centimetres) with males about 1.8 m, and females about 1.9m.
Diet
C. longimanus feeds mainly on pelagic cephalopods and bony fish. However, its diet is often far wider and less selective than this — it is known to eat threadfins, stingrays, sea turtles, sea birds, gastropods, squid, crustaceans, mammalian carrion and even rubbish dumped from ships. The bony fish it does feed on include lancetfish, oarfish, barracuda, jacks, dolphinfish, marlin (fish), tuna, and mackerels. Its method of obtaining food often include biting into a group of fish, or swimming through schools of tuna with an open mouth. When feeding with other species — it becomes aggressive.
Oceanic_Whitetip_Shark.png
Behavior
The Oceanic Whitetip is usually solitary and slow-moving, and tends to cruise near the top of the water column, covering vast stretches of empty water scanning for possible food sources. Sharks were known to mariners as 'sea dogs' until the 16th Century, and C. longimanus, the common ship-following shark, can indeed exhibit rather doglike behavior when its interest is piqued: When attracted to something that seems like food, its movements become more avid, and it will approach cautiously but stubbornly, retreating and maintaining the minimum safe distance if driven off, but ready for a rush of boldness if the opportunity presents. Whitetips aren't fast sharks, but like many slow-movers, they're capable of surprising bursts of quickness -- and while it is difficult to make claims of an animal's intelligence, the Oceanic Whitetip has an apparent cleverness that seems, like some of their behaviors, almost canine.
Groups are often formed when several nearby individuals converge on a food source, whereupon the fabled "feeding frenzy" may occur (a behavior not seen in coastal or inshore species of sharks). The frenzy seems triggered not by blood in the water per se, or by bloodlust, but by the species being especially high-strung and goal-directed when not pokily plying the open ocean, conserving energy between distant food events. C. longimanus is a competitive, opportunistic predator with great incentive to exploit the resource at hand, rather than avoiding trouble in favor of a possibly easier meal in the future — and the feeding frenzy is the equivalent of a midnight clearance sale at Macy's.
There seems to be a segregation by sex and size, at least in some parts of the world. Whitetips will follow schools of tuna or squid, and will follow groups of cetaceans such as dolphins and pilot whales as scavengers of the cetaceans' prey. They follow boats as well, and indeed seem to have a vital following-impulse, developed over countless millennia of baitfish migrations and doglike hope that the bigger guy might drop a piece of whatever he is eating.
Reproduction
Mating season is in early summer in the northwest Atlantic Ocean and southwest Indian Ocean. Viviparous (young hatch, live and are fed in utero by a placental sac), with litter size varying from 1 to 15 young. There is a gestation period of a year. Sexual maturity is reached near a length of 1.75 to 2 m for males and females, respectively, though they are born at a size of about 0.6 m.
Importance to humans
The Oceanic Whitetip is the most common shark in its range, and perhaps the most abundant large animal in the world. It is a commercially important species to the extent that its fins are prized for soup and its meat and oil frequently used -- although it more often appears on boats as by catch than on purpose. It steals fish from lines and snatches bait, and is considered more of a nuisance than a resource. The Oceanic Whitetip poses an extremely minimal threat to bathers or inshore sportsman, but a substantial one for humans caught in the open ocean in conditions in which they might be seen as likely prey.
Despite the greater notoriety of the Great White and other sharks who ply their trade nearer the shore, the Oceanic Whitetip is probably responsible for more fatal attacks on humans than all other species combined, by preying on those who are shipwrecked or downed from planes in the open ocean through disaster or war. These incidents are not included in common shark-attack indices for the 20th and 21st Century, but would appear to total in the thousands worldwide, with one incident alone, the torpedoing of the U.S.S. Indianapolis, on July 30th, 1945, giving a minimal figure of 60-80 killed by sharks. The Oceanic Whitetip, unlike the Great White and others, is abundant and highly opportunistic and aggressive, and will attack humans for food.
Divers are advised to approach the shark only with extreme caution — and hit it on the snout if it approaches.
References
- Leonard J. V. Compagno, Sharks of the Order Carcharhiniformes, Princeton University Press, 1988, ISBN 0-691-08453-X
- Leonard J. V. Compagno, Sharks of the World: An annotated and illustrated catalogue of shark species known to date, Food and Agriculture Organization of the United Nations, 1984
- William N. Eschmeyer, Special Publication of the Center for Biodiversity Research and Information, no. 1, vol 1-3, California Academy of Sciences, 1998, ISBN 0-940228-47-5
- Richard H. Backus, Stewart Springer and Edgar L. Arnold, Jr. A contribution to the natural history of the white-tip shark, Pterolamiops longimanus (Poey), 1956, Deep-Sea Research vol. 3
- A. J. Bass, J. D. D'Aubrey and N. Kistnasamy, Sharks of the east coast of southern Africa. 1. The genus Carcharhinus (Carcharhinidae), 1973, Oceanographic Research Institute, Durban
- Leonard J. V. Compagno, FAO Species Catalogue, Vol. 4, Parts 1 and 2, Sharks of the World, 1984, Rome: FAO
- Richard Ellis, The Book of Sharks, 1976, New York: Grosset & Dunlap
- Thomas H. Lineaweaver III and Richard H. Backus, The Natural History of Sharks, 1969, Philadelphia: Lippincourt.
- Reader's Digest, Sharks: Silent Hunters of the Deep, 1989, Sydney: Reader's Digest
- Jeremy Stafford-Deitsch, Shark: A Photographer's Story, 1988, San Francisco: Sierra Club Books
External links
- FishBase info for Oceanic Whitetipped (http://www.fishbase.org/Summary/SpeciesSummary.cfm?genusname=Carcharhinus&speciesname=longimanus)
- MarineBio: Oceanic Whitetip shark, Carcharhinus longimanus (http://marinebio.org/species.asp?id=89)
- http://www.ncf.carleton.ca/~bz050/whitetip.html
| Shark articles | |
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| Angel | Basking | Blacktip Reef | Blue | Bull | Carpet | Cat | Cookiecutter | Freshwater | Frilled | Goblin | Gray Reef | Grey Nurse | Great White | Hammerhead | Mako | Megamouth | Nurse | Oceanic Whitetip | Porbeagle | Requiem | River | Sand | Sandbar | Saw | Silky | Sleeper | Smooth dogfish | Thresher | Tiger | Whale (shark) | Whitetip reef | Wobbegong | Zebra / Leopard | |
| Extinct shark species | |
| Megalodon | Cladoselache | Squalicorax |