Great white shark

Great white sharks are perhaps best known for their depiction as man-eating sharks. They are one of the largest and strongest predators of marine mammals. They are located on the top of the food chain because their bodies are designed for being a predator. They are more agile and stronger than other fishes. They have extremely sensitive sensors on their nose which detect prey. Their torpedo-shaped body and sharp scales help itself to reduce friction. Their enormous bite force and regenerating teeth show they are born to be the strongest. They are carnivorous, feeding on marine mammals such as seals, and sea birds like cormorants and penguins. The population of the great white sharks is reducing rapidly because of the low reproductive rate, hunting, fishing and entertainment. Most of the body parts of great white shark can be sold in high prices.

Body Design
The average length of the great white shark is 4.5 m (15 ft). The female shark has a bigger body than male shark. Great white sharks have a torpedo-shaped body. This shape helps sharks to reduce friction. When you look at their scales, tiny pieces of sharp and rough scales are forming on their skin. They have strong dorsal, pectoral and caudal fins which make it possible to swim up to 24 km/hr (15 mph). They have five gill slits on the side of their body. Their body has countershading. On their ventral part they have white skin and on their dorsal part they have grey. Their snouts have an amazing sense that can sense a drop of blood in 100 liters of water and detect 0.005 microvolts.

Inside their mouth there are several rows of triangular sharp teeth which they can regenerate. These teeth are used to bite and tear the prey. They have a bite force of over 18,000 newtons (4,000 lbf). The great white sharks have a mouth that are 0.9 to 1.2 m wide and the upper and bottom teeth work together. While the bottom teeth hold the prey in place, the upper teeth tear the prey. They grab and cut the prey with the front two rows of their teeth. When the last row of teeth become unusable, the teeth rotate and fill the spaces.

By using a heat exchange system in their blood vessels, great white sharks can make their body temperature higher than the surrounding water.

Life Cycle
On average the great white shark lives about 30 years. Great white sharks have a low rate of reproduction. Unlike many other sharks who lay eggs, great white sharks are ovoviviparous (produce eggs that hatch inside the female's body). The female shark can only have 7-9 youngs, and they only reproduce twice while they are living. Newborn babies are more than 1 meter (about 3 feet) in length. The youngs of sharks grow 25cm in a year.

The length of gestation of the female sharks is about between 12 and 18 months. Male great white sharks become mature at 3.5 to 4 meters (about 11.5 to 13 feet) in length and about 10 years of age, and the females become sexually mature at 4.5 to 5 meters (about 15 to 16 feet) in length and 12 to 18 years of age. The mothers don't help the newborn babies after giving them a birth but instead they let the babies live independently. The baby sharks are capable predators as soon as they are born.

Ecology
The great white shark is located at the top of the food chain. The great white shark is carnivorous. They have a broad range of predation. They eat small bony fish to large bony fish. They also eat other sharks. They feed on marine mammals such as seals, and sea birds like cormorants and penguins. We can find great white shark in many oceans that are warm and temperate; water temperature between 12 and 24 degrees C (54 and 75 degrees F). They are usually coastal and offshore waters off the land. Most great white sharks are independent but there are some sharks moving in pairs or in small groups.

These sharks can go deep as 1,220 m (4,000 ft), and they can migrate a long distances. The great white shark living in California migrates to Hawaii for at least 100 days. Another example, the great white shark from South Africa swims to northwestern coast of Australia and back, which is 20,000 km (12,000 miles), for less than nine months. Why they migrate and what they do is unknown but researchers are guessing its because of seasonal feeding or mating. They are usually found in the United States (Atlantic Northeast and California), South Africa, Japan, Australia, New Zealand, Chile, and the Mediterranean.

Threats
Great white sharks seem abundant because they are in the top of the food chain, but they are rare. IUCN considers them vulnerable because they have low reproductive rates. The most serious problem is occurring by human. Researchers say that the population of great white shark has declined in several area up to 90% for the last 40-100 years. Great white sharks became a target of sports-fishing and hunting. People collect jaws, teeth, bones and mostly everything from the shark. People use shark's liver as a medicine. The trade of shark's fin has increased for the food purposes.

The most common way this shark gets caught is by commercial fisheries. The setlines, gillnets, traps, and other gears accidentally. This shark is vulnerable to sports fisheries, the curio trade, the oriental shark-fin trade and the public aquarium trade. In South Africa people sell fully intact jaws of great white shark at $20,000-$50,000 and US$600-$800 for individual teeth. During 1961-1990 in Australia, the shark catching game reduced a lot of great white sharks. Game fishing got popular because of the powerful resistance and the reputation as the most dangerous fish. To keep the great white shark from reducing, media services like news and entertainments have to show people how serious this problem is and tell people the realistic treatments. We must stop killing them from international games.

Video
Predation of Great white shark |yp9YKEO9e1w