Great White Shark



The great white shark, Carcharodon carcharias, also known as great white, white pointer, white shark, or white death, is a large lamniform shark found in coastal surface waters in all major oceans. The great white shark is very well known for its size, with the largest individuals known to have approached or exceeded 6.1 metres (20 ft) in length[3] and 2,268 kilograms (5,000 lb) in weight.[4] It reaches maturity at around 15 years of age and can have a life span of over 30 years. The great white shark is arguably the world's largest known extant macropredatory fish and is one of the primary predators of marine mammals. It is also known to prey upon a variety of other marine animals including fish, pinnipeds, and seabirds. It is the only known surviving species of its genus, Carcharodon.

The best selling novel Jaws and the subsequent blockbuster film by Steven Spielberg depicted the great white shark as a "ferocious man eater". In reality, humans are not the preferred prey of the great white shark.[5]

The IUCN treats the great white shark as vulnerable,[2] while it is included in Appendix II of CITES.[6

Etymology

Carolus Linnaeus gave the great white shark its first scientific name, Squalus carcharias in 1758. Sir Andrew Smith gave it the generic name Carcharodon in 1833, and in 1873 the generic name was identified with Linnaeus' specific name and the current scientific name Carcharodon carcharias was finalised. Carcharodon comes from the Greek words karcharos, which means sharp or jagged, and odous, which means tooth.[7]

Distribution and habitat
Great white sharks live in almost all coastal and offshore waters which have water temperature between 12 and 24 °C (54 and 75 °F), with greater concentrations in the United States (Atlantic Northeast and California), South Africa, Japan, Australia (especially New South Wales and South Australia), New Zealand, Chile, and the Mediterranean.[9] One of the densest known populations is found around Dyer Island, South Africa where much shark research is conducted.

It is an epipelagic fish, observed mostly in inland tributaries in the presence of rich game like fur seals, sea lions, cetaceans, other sharks, and large bony fish species. It is an open-ocean dweller and has been recorded at depths of around 1,220 m (4,000 ft).[10] These findings challenge the traditional notion about the great white as being a coastal species.[10]

According to a recent study, California great whites have migrated to an area between Baja California and Hawaii known as White Shark Café, to spend at least 100 days before migrating back to Baja. On the journey out, they swim slowly and dive down to around 900 m (3,000 ft). After they arrive, they change behavior and do short dives to about 300 m (1,000 ft) for up to 10 minutes. Another white shark tagged off the South African coast swam to the southern coast of Australia and back within the year. This refuted traditional theories that white sharks are coastal territorial predators and opens up the possibility of interaction between shark populations that were previously thought to be discrete. Why they migrate and what they do at their destination is still unknown. Possibilities include seasonal feeding or mating.[11]

A similar study tracked a great white shark from South Africa swimming to Australia's northwestern coast and back, a journey of 20,000 km (12,000 mi; 11,000 nmi) in under 9 months.[12]

Anatomy and appearance
The great white shark has a robust large conical snout. The upper and lower lobes on the tail fin are approximately the same size (like some mackerel sharks).

Great whites display countershading, having a white underside and a grey dorsal area (sometimes in a brown or blue shade) that gives an overall "mottled" appearance. The coloration makes it difficult for prey to spot the shark because it breaks up the shark's outline when seen from the side. From above, the darker shade blends with the sea and from below it exposes a minimal silhouette against the sunlight.

Great white sharks, like many other sharks, have rows of serrated teeth behind the main ones, ready to replace any that break off. When the shark bites it shakes its head side to side, helping the teeth saw off large chunks of flesh.

Size
Males reach maturity at 3.5–4.0 metres (11–13 ft), and females at 4.5–5.0 metres (15–16 ft). Adults on average are 4–5.2 metres (13–17.1 ft) long and have a mass of 680–1,100 kilograms (1,500–2,400 lb). Females are generally larger than males. It is widely accepted that the great white shark can approach 6.1 m (20 ft) in length and 1,900 kg (4,200 lb) in weight.[3] However, the maximum size is still subject to hot debate because such reports are often rough estimations or speculations performed under questionable circumstances.[14]

A number of very large great white shark specimens have been recorded.[15] For decades, many ichthyological works, as well as the Guinness Book of World Records, listed two great white sharks as the largest individuals: a 10.9 m (36 ft) great white captured in Southern Australian waters near Port Fairy in the 1870s, and a 11.3 m (37 ft) shark trapped in a herring weir in New Brunswick, Canada in the 1930s. Some researchers question these measurements' reliability, noting they were much larger than any other accurately reported sighting. The New Brunswick shark may have been a misidentified basking shark, as the two have similar body shapes. The question of the Port Fairy shark was settled in the 1970s, when J. E. Randall examined the shark's jaws and "found that the Port Fairy shark was of the order of 5 m (17 ft) in length and suggested that a mistake had been made in the original record, in 1870, of the shark's length".[16]

According to J. E. Randall, the largest white shark reliably measured was a 6.0 m (19.7 ft) individual reported from Ledge Point, Western Australia in 1987.[16] Another great white specimen of similar size has been verified by the Canadian Shark Research Center: a female caught by David McKendrick of Alberton, Prince Edward Island in August 1988 in the Gulf of St. Lawrence off PEI. This female great white was 6.1 m (20 ft) long.[3] However, a larger great white shark specimen was verified by T. C. Tricas and J. E. McCosker in 1984. This specimen was 6.4 m (21 ft) long and had a body mass of about 3,324 kg (7,330 lb).

Several great white sharks caught in modern times have been estimated to be more than 7 m (23 ft) long,<sup class="reference" id="cite_ref-GWS_17-0">[18] but these claims have received some criticism.<sup class="reference" id="cite_ref-EllisMcCosker_13-1">[14] <sup class="reference" id="cite_ref-GWS_17-1">[18] However, J. E. Randall believed that great white shark may have exceeded 6.1 m (20 ft) in length.<sup class="reference" id="cite_ref-SAWP_15-2">[16] A great white shark was captured near Kangaroo Island in Australia on April 1, 1987. This shark was estimated to be more than 7 m (23 ft) long by Peter Resiley,<sup class="reference" id="cite_ref-SAWP_15-3">[16] <sup class="reference" id="cite_ref-18">[19] and has been designated as KANGA.<sup class="reference" id="cite_ref-GWS_17-2">[18] Another great white shark was caught in Malta by Alfredo Cutajar on April 16, 1987. This shark was also estimated to be around 7.13 m (23.4 ft) long by John Abela and has been designated as MALTA.<sup class="reference" id="cite_ref-GWS_17-3">[18] However, criticism occurred — Cappo used shark size estimation methods proposed by J. E. Randall to suggest that KANGA specimen was 5.8–6.4 m (19–21 ft) long.<sup class="reference" id="cite_ref-GWS_17-4">[18] In the similar fashion, I. K. Fergusson also used shark size estimation methods proposed by J. E. Randall to suggest that MALTA specimen was 5.3–5.7 m (17–19 ft) long.<sup class="reference" id="cite_ref-GWS_17-5">[18] However, photographic evidence suggested that these specimens were larger than the size estimations yielded through Randall's methods.<sup class="reference" id="cite_ref-GWS_17-6">[18] Thus, a team of scientists, H. F. Mollet, G. M. Cailliet, A. P. Klimley, D. A. Ebert, A. D. Testi, and L. J. V. Compagno, reviewed the cases of KANGA and MALTA specimens in 1996 to resolve the dispute by conducting a comprehensive morphometric analysis of the remains of these sharks and re-examination of photographic evidence in an attempt to validate the original size estimations and their findings were consistent with them. The findings indicated that estimations by P. Resiley and J. Abela are reasonable and cannot be ruled out.<sup class="reference" id="cite_ref-GWS_17-7">[18]

A close contender in size is the Tiger shark, Galeocerdo cuvier, with largest specimen reported to have been 7.4 metres (24 ft) in length along with a mass of 3,110 kilograms (6,900 lb).<sup class="reference" id="cite_ref-19">[20] Some other macropredatory sharks such as Greenland Shark, Somniosus microcephalus, and Pacific sleeper shark, Somniosus pacificus, are also known to rival these sharks in length.<sup class="reference" id="cite_ref-20">[21] <sup class="reference" id="cite_ref-21">[22] The question of maximum weight is complicated by the unresolved question of whether or not to include the shark's stomach contents when weighing the shark. With a single bite a great white can take in up to 14 kg (31 lb) of flesh, and can consume several hundred kilograms of food.

The largest great white recognized by the International Game Fish Association (IGFA) is one landed by Alf Dean in south Australian waters in 1959, weighing 1,208 kg (2,660 lb).<sup class="reference" id="cite_ref-EllisMcCosker_13-2">[14] Several larger great whites caught by anglers have since been verified, but were later disallowed from formal recognition by IGFA monitors for rules violations.