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       JAWS (THE GREAT WHITE)                           

 

        

 

The great white shark, Carcharodon carcharias, also known as is an exceptionally large lamnifore sharks found in coastal surface waters in all major oceans. Reaching lengths of about 6 metres (20 ft) and weighing almost 2,000 kg's, the great white shark is the world's largest known predatory fish. It is the only known surviving species of its genus, Carcharodon. They are also regarded as an apex predator with its only real threats from humans and occasionally killer whales, which have been known to feed on great whites.

The great white shark has a robust large conical-shaped snout. It has almost the same size upper and lower lobes on the tail fin (like most mackerel sharks, but unlike most other sharks). It is pale to dark grey and has a white stomach. Great white sharks have a white belly and a grey back. The coloration makes it difficult for prey to spot the shark because it breaks up the shark's outline when seen from a lateral perspective. When viewed from above, the darker shade blends in with the sea.

Great white sharks, like many other sharks, have rows of teeth behind the main ones, allowing any that break off to be rapidly replaced. Their teeth are unattached to the jaw and are retractable, like a cat's claws, moving into place when the jaw is opened. Their teeth also rotate on their own axis (outward when the jaw is opened, inward when closed). The teeth are linked to pressure and tension-sensing nerve cells. This arrangement seems to give their teeth high tactile sensitivity. A great white shark's teeth are serrated and when the shark bites it will shake its head side to side and the teeth will act as a saw and tear off large chunks of flesh. Great white sharks often swallow their own broken off teeth along with chunks of their prey's flesh. These teeth frequently cause damage to the great white shark's digestive tract. However great white sharks often feed on stingrays and swallow the 'sting' as well, the barbed sting often getting stuck in the shark's intestines.  A great white shark caught off Hualien County, Taiwan, in 1997. Reportedly almost 7 m in length and weighing 2500 kg, it is possibly the largest specimen ever recorded.

The average length of a full-grown great white shark is 4 to 4.8 metres (13.3 to 15.8 ft), with a weight of 680 to 1,100 kilograms (1,500 to 2,450 lbs), females generally being larger than males. But the question of the maximum size of a great white shark has been subject to much debate, conjecture, and misinformation. Richard Ellisand John E Mckosker, both academic shark experts, devote a full chapter in their book, The Great White Shark (1991), to analyzing various accounts of extreme size.

Great white sharks, like all other sharks, have an extra sense given by the Ampullae of lorenzini, which enables them to detect the electromagnetic field emitted by the movement of living animals. Every time a living creature moves it generates an electrical field and great whites are so sensitive they can detect half a billionth of a volt. This is equivalent to detecting a flashlight battery from 1,600 kilometres (1,000 miles) away.

To more successfully hunt fast moving and agile prey such as sea lions, the poikilothermic great white shark has developed adaptations that allow it to maintain a body temperature warmer than the surrounding water. One of these adaptations is a "rete mirabile" (Latin for "wonderful net"). This close web like structure of veins and arteries, located along each lateral side of the shark conserves heat by warming the cooler arterial blood with the venous blood that has been warmed by the working muscles. This keeps certain parts of the body running at temperatures up to 14 C above the surrounding water, while the heart and gills remain at sea-temperature. When conserving energy (a great white shark can go weeks between meals), the core body temperature can drop to match the surroundings.

Great white sharks primarily eat fish, smaller sharks, turtles, dolphins, whale carcasses and pinnipeds such as seals and sea lions. Great whites have also been known to eat objects that can't be digested. In great white sharks above 3.41 metres (11 ft, 2 in) a diet consisting of a higher proportion of mammals has been observed.

A great white shark primarily uses its extra senses (i.e, electrosense and mechanosense) to locate prey from far off. Then, the shark uses smell and hearing to further verify that its target is food. At close range, the shark utilizes sight for the attack.

The great white shark will often deliver a massive disabling bite and then back off to allow the prey to expire. This tactic allows the animal to avoid combat with dangerous prey, such as sea lions. It also has allowed occasional rescue of humans bitten by the animal, though it appears to attack humans mostly in error.

The great white shark is the only shark known to regularly lift its head above the sea surface to gaze at other objects such as prey; this is known as "spy hopping". This behaviour has also been seen in at least one group of black tip reef sharks, but this might be a behaviour learned from interaction with humans (it is theorized that the shark may also be able to smell better this way, because smells travel through air faster than through water). They are very curious animals, and can display a high degree of intelligence and personality when conditions permit (such as in the clear waters off of Mexico.

There is still a great deal that is unknown about great white shark behavior, such as their mating habits. Birth has never been observed, but several pregnant females have been examined. Great white sharks are ovoviviparous, the eggs developing in the female's uterus, hatching there and continuing to develop until they are born, at which point they are perfectly capable predators. The embryos can feed off unfecundated eggs. The delivery takes place in the period transitioning spring and summer.

The young, which number 8 or 9 (with a maximum of perhaps 14) for a single delivery, are about 1.5 metres (5 ft) long when born. Their teeth are provided with small side cusps. They grow rapidly, reaching 2 metres of length in the first year of life. Almost nothing, however, is known about how and where the great white mates. There is some evidence that points to the near-soporific effect resulting from a large feast (such as a whale carcass) possibly inducing mating.

A great white shark can reproduce when a male's length is around 3.8 metres (12 ft) and a female's length is around 4 to 4.8 metres (13.3 to 15.8 ft). Their lifespan has not been definitively established, though many sources estimate 30 to 40 years. It would not be unreasonable to expect such a large marine animal to live longer however.

 

              

 

 

 

 

 

 

 

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