Great white shark facts for kids
|Great white shark|
|Range (in blue); in the dark blue areas the sharks are more common|
The great white shark (Carcharodon carcharias) is a species of shark. They are world's largest living predatory fish. Mature sharks may grow up to 6.4 m (21 ft) in length and 3,324 kg (7,328 lb) in weight). There also have been a few reports of great white sharks measuring over 8 m (26 ft). This shark reaches its sexual maturity around 15 years of age. The lifespan of great white shark may be as long as 70 years or more. Great white sharks can accelerate to speeds over 56 km/h (35 mph).
Great white sharks, like many other sharks, have rows of serrated teeth behind the main ones. The first two rows of the teeth are used for grabbing and cutting the animals they eat, while the other teeth in the last rows replace the front teeth when they are broken, worn down, or when they fall out. The teeth have the shape of a triangle with jags on the edges. Great white sharks eat fish and other animals, for example seals and sea lions.
The great white shark has no natural predators other than the Orca. Some orcas have discovered they can paralyse the shark by flipping it upside-down. Then they hold the shark still with their mouth, and that suffocates it (sharks get oxygen by moving through the water). That aside, they are apex predators of marine mammals.
The bestselling novel Jaws by Peter Benchley and the film by Steven Spielberg show the great white shark as a "ferocious human eater". In real life, humans are not the preferred food of the great white shark. However, of all shark species, the great white shark has the largest number of fatal unprovoked attacks on humans.
The great white shark is a shark. A shark is a type of cartilaginous fish. The back of the shark has a grey color and the underside is colored white. The sharks have three main fins: the dorsal (on back) and two pectoral fins (on the sides).
There are five gill slits on great white sharks.
Great white sharks have rows of teeth behind the main ones, but these are folded back or within the gum line. They have about 24 exposed teeth on their top and lower jaws. When one of the main teeth break off, there are teeth always ready to replace it. The great white shark shakes its head side-to-side when it bites. This helps the teeth cut off large chunks of flesh.
The great white becomes an adult about nine years after its birth. The growth of the great white shark is about 25-30 centimetres per year and they grow to an average size of 4.5 meters. The largest can be as much as 6.4 meters in length. Their liver can weigh up to about 24 percent of it's own body weight.
Adults on average are 4–5.2 m (13–17 ft) long and have a mass of 680–1,100 kg (1,500–2,430 lb). Females are generally larger than males. The great white shark can reach 6.4 m (21 ft) in length and 3,324 kg (7,328 lb) in weight. Among living cartilaginous fish, only the whale shark (Rhincodon typus), the basking shark (Cetorhinus maximus) and the giant manta ray (Manta birostris), are larger and heavier. These three species are generally quite gentle and filter feed on very small organisms.
Great white sharks are carnivorous and prey upon fish (e.g. tuna, rays, other sharks), cetaceans (i.e., dolphins, porpoises, whales), pinnipeds (e.g. seals, fur seals, and sea lions), sea turtles, sea otters, and seabirds. Great whites have also been known to eat objects that they are unable to digest. Upon approaching a length of nearly 4 metres (13 ft), great white sharks begin to target predominately marine mammals for food. These sharks prefer prey with a high content of energy-rich fat. Shark expert Peter Klimley used a rod-and-reel rig and trolled carcasses of a seal, a pig, and a sheep from his boat in the South Farallons. The sharks attacked all three baits but rejected the sheep carcass.
The great white shark's reputation as a ferocious predator is well-earned, yet they are not (as was once believed) indiscriminate "eating machines". They are ambush hunters, taking prey by surprise from below. Near Seal Island, in South Africa's False Bay, shark attacks most often occur in the morning, within 2 hours after sunrise, when visibility is poor. Their success rate is 55% in the first 2 hours, falling to 40% in late morning after which hunting stops.
Hunting techniques vary by species of the prey. Off Seal Island, the sharks ambush brown fur seals from below at high speeds, hitting the seal mid-body. They go so fast that they can completely leave the water. The peak burst speed of these sharks is largely accepted in the scientific community to be above 40 kilometres per hour (25 mph). However further precision is still speculative. They have also been observed chasing prey after a missed attack. Prey is usually attacked at the surface.
Off California, sharks immobilize northern elephant seals with a large bite to the hindquarters (which is the main source of the seal's mobility) and wait for the seal to bleed to death. This technique is especially used on adult male elephant seals which can be as large or larger than the hunter and are potentially dangerous adversaries. Prey is normally attacked sub-surface. Harbour seals are taken from the surface and dragged down until they stop struggling. They are then eaten near the bottom. California sea lions are ambushed from below and struck mid-body before being dragged and eaten.
White sharks also attack dolphins and porpoises from above, behind or below to avoid being detected by their echolocation. Targeted species include dusky dolphins, Risso's dolphins, bottlenose dolphins, Humpback dolphins, harbour porpoises, and Dall's porpoises. Close encounters between dolphins and predatory sharks often result in evasive responses by the dolphins. However, in rare cases, a group of dolphins may chase a single predatory shark away in an act of defense. White shark predation on other species of small cetacean has also been observed. In August 1989, a 1.8 metres (5.9 ft) juvenile male pygmy sperm whale, Kogia breviceps, stranded in central California with a bite mark on its caudal peduncle from a great white shark. In addition, white sharks also attack and prey upon beaked whales.
Even though the great whites are known to generally avoid conflicts with each other, the phenomenon of cannibalism is not alien to this species. Large individuals may aggressively interact intraspecifically with small individuals. A 3 m (9.8 ft) long great white shark was nearly bitten into two by a reportedly 6 m (20 ft) long great white shark in Stradbroke Island, near Brisbane in Australia.
White sharks also scavenge on whale carcasses. In one such documented incident, white sharks were observed scavenging on a whale carcass alongside tiger sharks.
Where they live
Great white sharks live in the sea. They live near the coast, in all warm waters. They occasionally make dives into the deep water of open oceans. They can be in water as shallow as three feet deep, and as deep as 1,280 metres.
They may swim near:
- Western Atlantic: from Newfoundland to Florida, Bahamas, Cuba, Northern Gulf of Mexico, Brazil, Argentina, Guadeloupe;
- East Atlantic: France, Senegal, Ghana, Democratic Republic of the Congo
- Mediterranean: North Africa, South of France, West and South coast of Italy, Croatia, Malta, Greece, ;
- Indian Ocean: South Africa, Seychelles, Red Sea
- Western Pacific: Japan, Korea, China, Philippines, Australia, New Zealand;
- Central Pacific: Hawaii
- Eastern Pacific: from Alaska to California, and from Panama to Chile.
Research has shown that the sharks of northern California are genetically different to other shark populations. DNA evidence shows the population separated from other great whites about 200,000 years ago (during the Pleistocene Era). By tagging the sharks they also learned that they are generally alone, but follow the same route through the ocean, and stay in the same places. From January to July they live near Hawaii, and then move to Californian waters between August and December.
Sometimes, sharks attack human beings. When sharks see a new object, for example, a surfboard, they bite it to know what kind of object it might be. Sometimes, sharks see the shadow of surfers and attack them because they think they are seals.
Some people think that humans are not good food for great white sharks, because the sharks' digestion might be too slow to cope with the human body's high ratio of bone to muscle and fat. It might be argued that because of this nearly all attacks by great whites do not continue after the first bite.
Sharks are opportunistic predators. This means that they are not very picky on what they feed on. This behaviour has been observed when the animals completely consumed piecemeal bait. The explanation given is that the tactics generally involve biting prey once, so that the prey bleeds to death before the shark moves in to feed. Other large mammals, such as seals and dolphins also seem to have this tactic, as it minimizes the risk of the predator injuring itself. In most cases, humans tend to escape quickly after the first bite so that they are not consumed, simply bitten. Deaths in such cases are generally caused by loss of blood from the first wound. In cases where attacks have occurred and the victim has been unable to escape quickly, partial or whole consumption has occurred; lone divers are especially at risk of this. Most attacks also seem to occur in waters where it is hard to see or where the shark is confused, but this is unlikely given that the shark is in its natural hunting environment with highly developed senses.
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Great white shark Facts for Kids. Kiddle Encyclopedia.