Great white shark

The great white shark (Carcharodon carcharias), commonly known as the great white or the white shark, is a species of large mackerel shark which can be found in the coastal surface waters of all the major oceans.

The great white shark is notable for its size, with larger female individuals growing to 6.1 m (20 ft) in length and 1,950 kg (4,300 lb) in weight at maturity.

However most are smaller, males measuring 3.4 to 4.0 m (11 to 13 ft) and females 4.6 to 4.9 m (15 to 16 ft) on average.

According to a 2014 study the lifespan of great white sharks is estimated to be as long as 70 years or more, well above previous estimates, making it one of the longest lived cartilaginous fish currently known.

According to the same study, male great white sharks take 26 years to reach sexual maturity, while the females take 33 years to be ready to produce offspring. Great white sharks can swim at speeds of over 56 km/h (35 mph), and can swim to depths of 1,200 m (3,900 ft).

The great white shark has no known natural predators other than, on very rare occasion, the killer whale. 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 and seabirds. It is the only known surviving species of its genus Carcharodon, and is ranked first in having the most recorded shark bite incidents on humans.
The IUCN list the great white shark as a vulnerable species, while it is included in Appendix II of CITES.

The novel Jaws by Peter Benchley and the subsequent film by Steven Spielberg depicted the great white shark as a "ferocious man eater". Humans are not the preferred prey of the great white shark, but, nevertheless, the great white is responsible for the largest number of reported and identified fatal unprovoked shark attacks on humans. The great white shark has also been called the white pointer or white death.

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 (Northeast and California), South Africa, Japan, Oceania, Chile, and the Mediterranean including Sea of Marmara and Bosphorus. One of the densest known populations is found around Dyer Island, South Africa.

The great white is an epipelagic fish, observed mostly in the presence of rich game, such as fur seals (Arctocephalus ssp.), sea lions, cetaceans, other sharks, and large bony fish species. In the open ocean, it has been recorded at depths as great as 1,200 m (3,900 ft). These findings challenge the traditional notion that the great white is a coastal species.

According to a recent study, California great whites have migrated to an area between Baja California Peninsula and Hawaii known as the 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 ten minutes. Another white shark that was tagged off of the South African coast swam to the southern coast of Australia and back within the year. A similar study tracked a different 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 nine months. These observations argue against traditional theories that white sharks are coastal territorial predators, and open up the possibility of interaction between shark populations that were previously thought to have been discrete. The reasons for their migration and what they do at their destination is still unknown. Possibilities include seasonal feeding or mating.

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 which is similar to some mackerel sharks. A great white displays countershading, by 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

In great white sharks, sexual dimorphism is present, and females are generally larger than males. Male great whites on average measure 3.4 to 4.0 m (11 to 13 ft) long, while females at 4.6 to 4.9 m (15 to 16 ft). Adults of this species weigh 522–771 kg (1,151–1,700 lb) on average, however mature females can have an average mass of 680–1,110 kg (1,500–2,450 lb). The largest females have been verified up to 6.1 m (20 ft) in length and an estimated 1,950 kg (4,300 lb) in weight, perhaps up to 2,268 kg (5,000 lb). The maximum size is subject to debate because some reports are rough estimations or speculations performed under questionable circumstances. Among living cartilaginous fish, only the whale shark (Rhincodon typus), the basking shark (Cetorhinus maximus) and the giant manta ray (Manta birostris), in that order, average larger and heavier. These three species are generally quite docile in disposition and given to passively filter-feeding on very small organisms. This makes the great white shark the largest extant macropredatory fish. Great white sharks are at around 1.2 m (3.9 ft) when born, and grow about 25 cm (9.8 in) each year.

According to J. E. Randall, the largest white shark reliably measured was a 5.94 m (19.5 ft) individual reported from Ledge Point, Western Australia in 1987. 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 Prince Edward Island. This female great white was 6.1 m (20 ft) long. However, there was a report considered reliable by some experts in the past, of a larger great white shark specimen from Cuba in 1945. This specimen was 6.4 m (21 ft) long and had a body mass estimated at 3,324 kg (7,328 lb). However, later studies also revealed that this particular specimen was actually around 4.9 m (16 ft) in length, a specimen in the average maximum size range.

The largest great white recognized by the International Game Fish Association (IGFA) is one caught by Alf Dean in the south Australian waters in 1959, weighing 1,208 kg (2,663 lb). Several larger great whites caught by anglers have since been verified, but were later disallowed from formal recognition by IGFA monitors for rules violations.