Biology

White sharks can swim at speeds up to 25 miles per hour in short bursts, and have been observed leaping out of the water in pursuit of prey.

The white shark

(Carcharodon carcharias) is a legendary hunter immortalized in the book and motion picture Jaws. Dating back 50 million years or more, it's the world's largest predatory fish. It can reach 22 feet (6.7 meters) in length and weigh more than two tons (1,800 kilograms). It's an apex predator—the animal at the top of the food web, with no natural predators other than humans.

Young white sharks are believed to eat fishes, rays and other sharks. Adults eat larger prey, including pinnipeds (sea lions and seals), small toothed whales, sea otters and sea turtles. They also eat carrion (dead animals that they have found floating in the water).

Because they are highly migratory animals found in oceans around the world, little is known about their life history. They may live 20 years or more. They are able to sense minute amounts of blood in the water and the faint electrical fields given off by the bodies of potential prey species. They can swim at speeds up to 25 miles per hour in short bursts, and have been observed leaping out of the water in pursuit of prey. Females give birth to a litter of two to 14 live pups that are up to five feet long. The pups swim away from the mother immediately after birth; there is no maternal care-giving.

Adaptations for Survival

The white shark is able to maintain a body temperature 10-18 deg. F above the temperature of the surrounding water. This increased temperature is accomplished through a highly developed system of countercurrent heat exchange in the circulatory system. This system prevents heat from escaping as blood circulates through the gills and near the body surface. Warm muscles are able to contract more rapidly than cold muscles; thus an elevated body temperature allows muscles to work efficiently in cold surface water and when the shark dives to deep, cold water to hunt fishes and squids.

No Silverware Required

The jaws of a white shark are filled with very sharp teeth—up to three inches long and numbering up to 3,000 at any one time. The narrow teeth on the bottom grab and hold prey, and the triangle-shaped teeth on top are for cutting. The edges of the teeth have serrations on them, like a saw, to help them cut more easily.	Different types of sharks have teeth of different shapes. In general, the shape of a shark's tooth has to do with the type of food it eats and the way it hunts.	A shark has several rows of teeth in its mouth. Sharks bite with the outer row of teeth, but eventually these fall out. A tooth from the row behind moves up to take its place.
Scientists have determined that white shark biting is not a haphazard series of chomps, but rather a pre-determined progression. First, white sharks lift their snouts as much as 40 degrees and drop their lower jaws, opening their mouths to a suitable size for the food (left image). Then their upper jaws protrude, producing the startling image of the upper jaw, teeth, gums and connective tissue thrust forward from the roof of their mouths (right image). Next, they lift their lower jaws and trap their prey so it can't escape. Finally, their upper jaws retract and their snouts drop, applying the force necessary to take a single bite.

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