Fish Disection- Solider fish

Great White Shark

 The great white shark is the world's largest known predatory fish. It has 3,000 teeth, yet does not chew its food. Sharks rip their prey into mouth-sized pieces which are swallowed whole. The shark’s heavy, torpedo-shaped body allows it to cruise efficiently for long periods of time, and then suddenly switch to high speed bursts in pursuit of prey—sometimes leaping out of the water. It feeds on a broad spectrum of prey, from small fish, such as halibut, to large seals and dolphins.

 

As large and powerful predators, great white sharks play an important role at the top of the marine food chain. Despite its fame and reputation, little is actually known about the great white shark’s   biology and behavior.

 

 The great white shark, Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a species of large lamniform shark which can be found in the coastal surface waters of all the major oceans

Taxonomy

In 1758, Carolus Linnaeus gave the great white shark its first scientific name, Squalus carcharias. Later, Sir Andrew Smith gave it Carcharodon as its generic name in 1833, and also 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,

Ancestry and fossil record

The great white shark came into existence during the mid-Miocene epoch. The earliest known fossils of the great white shark are about 16 million years old.^[1] However, the phylogeny of the great white is still in dispute. The original hypothesis for the great white's origins is that it shares a common ancestor with a prehistoric shark, such as the C. megalodon. Similarities among the physical remains and the extreme size of both the great white and C. megalodon led many scientists to believe these sharks were closely related, and the name Carcharodon megalodon was applied to the latter. However, a new hypothesis proposes that the C. megalodon and the great white are distant relatives (albeit sharing the family Lamnidae). The great white is also more closely related to an ancient mako shark, Isurus hastalis, than to the C. megalodon. In addition, the new hypothesis assigns C. megalodon to the genus Carcharocles, which also comprises the other megatoothed sharks; Otodus obliquus is the ancient representative of the extinct Carcharocles lineage.^[11]

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, Oceania, Chile, and the Mediterranean.^[12] One of the densest known populations is found around Dyer Island, South Africa, where almost all of the shark research is done.
The great white is an epipelagic fish, observed mostly in the presence of rich game, such as fur seals, sea lions, cetaceans, other sharks, and large bony fish species. In the open ocean, it has been recorded at depths as great as 4,000 ft (1,200 m).^[13] These findings challenge the traditional notion about the great white as being a coastal species.^[13]
According to a recent study, California great whites have migrated to an area between Baja California 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. 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 have been discrete. The reasons for their migration and what they do at their destination is still unknown. Possibilities that may support this idea include seasonal feeding or mating.^[14] 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 nine months.^[15]

Anatomy and appearance

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.^[16]

Size

Great white shark which is allegedly 6.4 m (21 ft) long and weighing about 3,175 kg (7,000 lb).^[17]

Among living cartilaginous fish, only the Basking and Whale Sharks and the Manta Ray average larger and heavier. These three species are generally docile in disposition and given to passively feeeding on very small organisms.^[18] Males reach maturity at 3.5–4.0 m (11–13 ft) long and females at 4.5–5.0 m (15–16 ft) long. Adults on average are 4–5.2 m (13–17.1 ft) long and have a mass of 680–1,100 kg (1,500–2,400 lb). Females are generally larger than males. The great white shark can reach 6.1 m (20 ft) in length and 1,900 kg (4,200 lb) in weight.^[3] The maximum size is subject to debate because some reports are rough estimations or speculations performed under questionable circumstances.^[19]
A number of very large great white shark specimens have been recorded.^[20] For decades, many ichthyological works, as well as the Guinness Book of World Records, listed two great white sharks as the largest individuals: In the 1870s, a 10.9 m (36 ft) great white captured in southern Australian waters, near Port Fairy, 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. This 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".
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.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, 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).^[22]