How Great White Sharks Work

The great white shark has been involved in some of the most chilling attacks on humans. In 1985, Australian Shirley Ann Durdin was torn in two and then devoured by a white shark. Rodney Fox had his lungs and stomach ripped open and required more than 360 stitches in a 1963 attack [source: Rodney Fox]. In 2008, Dave Martin was killed in California when a great white bit off his legs.

The great white shark does outrank all other sharks in the number of shark attacks. As of May 2020, the great white had racked up 326 unprovoked attacks, resulting in 52 fatalities; this far outpaces the runner-up tiger shark (129 unprovoked attacks and 34 deaths) and the third-place bull shark (116 unprovoked attacks and 25 deaths) [source: International Shark Attack File].

Why are the numbers so high? One factor to keep in mind is that great whites are easily recognizable, particularly if they leave a tooth or two in their victims. This means that more attacks are specifically attributed to them than other, less identifiable species [source: Carey]. There may also be a mind-set that great white sharks are guilty in a shark attack until proven innocent. Whether this bias is fair or not, scientists are quick to remind us that the odds of actually being attacked by any shark are very small.

Are humans especially delicious to great white sharks? Probably not, according to scientists who've studied the stomach contents of these sharks. Humans, because of their muscle content, aren't a very good meal for great whites, who crave fatty blubber. Many shark attack victims live to tell their tale because the shark takes a bite, as if to taste it. While this will be small comfort to anyone ever trapped in the mouth of a shark, it may just be a case of mistaken identity. Think about someone lying on a surfboard, their arms and legs out to the side to paddle and kick. From below, this shape might resemble a seal.

The great white is no doubt dangerous, but if you're trying to decide whether to go swimming, it might be worth remembering that elephants are more deadly than great whites [source: Carey]. A common adage in the shark world now is that man is a much greater danger to sharks than sharks have ever been to man. These sharks are hunted for sport and also for their parts, including their teeth and their fins.

But what does the great white shark hunt, if not humans? Find out next.

Like some of us, the great white prefers a fatty meal to one with lots of protein. That's why its main prey item is the pinniped, an aquatic carnivore like a seal or a sea lion. As we mentioned, humans are generally too muscular and lean for a typical shark meal, but a seal might be 50 percent fat, representing a very efficient meal for great whites [source: Carey]. They'll also dine on other fishes and occasionally sea turtles. The great white shark consumes approximately 11 tons of food in one year (for comparison's sake, a 150-pound (68-kilogram) human being wolfs down about half a ton) [source: Parker].

While sharks are equipped with impressive noses and ears that help them to hunt their prey, the great white seems to rely most heavily on its sense of vision. It scopes out the water's surface for seals and then approaches them from underwater. One scientist conducted a study in which he presented a great white shark with a plywood seal-shaped board and a square board, and found that the great white made more passes at the seal-shaped board [source: Klimley].

That's a choice between an unfamiliar object (square) and a familiar one (seal), though. Whenever an object was presented by itself, the great white went to investigate -- one reason why swimmers are warned not to go into shark-infested waters alone [source: Martins, Knickle]. The white shark is known for its curiosity and may examine solitary and vulnerable objects to determine if they're edible.

Once the shark has spied something to try, it makes its approach. Scientists have identified several different ways the great white moves towards its prey:

[sources: Tricas and Martins, Knickle]

The first bite serves several important functions. Of course, it's designed to disable the prey. Seals are fast and don't give up without a fight, sometimes biting and clawing the shark. That bite starts the process of exsanguination, or bleeding to death, so that the shark doesn't suffer any injury in the course of hunting. Scientists have observed sharks taking that bite, waiting until the pinniped bleeds to death and then returning to feast on the carcass.

But that bite must also appeal to the shark's discerning palate because sharks sometimes reject the prey. Scientists don't know if the choice is based on taste, or if the shark is able to tell in that bite how fatty the meal is, and thus if it's worth the energy expenditure of the hunt.

Let's take a closer look at the great white's bite. On the next page, we'll go inside those fearsome jaws.

Any discussion of great white anatomy should start with the infamous jaws that gave Peter Benchley's tome a title. In fact, the great white shark's scientific name is Carcharodon carcharias, which means "ragged tooth" in Latin and shows that this shark's teeth have always been an important trait.

The great white has about 3,000 triangular teeth. When the shark moves in to bite its prey, its jaws extend forward as its head recedes back. The lower jaw strikes first, stabbing the prey with serrated blades. Then the upper jaw descends, and the teeth fit together perfectly so that whatever's inside is not going anywhere anytime soon. This whole process, from the head lifting to dropping back in place, takes about 0.99 seconds [source: Tricas].

The great white doesn't chew its food; instead, it holds the prey locked in those teeth and shakes its head from side to side, tearing off bits of flesh and blubber. The strength of the bite is estimated at 1 ton per square inch, with the great white able to consume about 20 to 30 pounds (9.1 to 13.6 kilograms) of flesh with one chomp. The great white's bite is about twice as strong as that of a lion [source: Parker].

To look at the great white's snout, you wouldn't think such impressive teeth were waiting -- the snout is fairly short and cone-shaped. The rest of the great white's body is torpedo-shaped and ends with a symmetrical caudal fin, or tail.

The great white takes its name from its white belly, but it's not white all over. On top, it's gray, or sometimes brown. This coloring aids the great white as it stalks its prey. From below, the white underside blends in with the sky above, while from the top of the water, the shark is indistinguishable from the ocean floor below. Most great whites also have a black spot near their pectoral fin.

The great white is the largest predatory fish in the sea, a fact that no doubt helps to drive humans' fear of being eaten by one. The maximum length for a great white appears to be about 20 feet (6 meters). While the great white isn't the biggest shark (an honor that belongs to the whale shark), the only sharks that are bigger eat plankton and small schools of fish. The great white tips the scales at 4,500 pounds (2,041 kilograms).

One thing that sets the great white apart from a lot of other sharks and other fish is that it's warm-bl­ooded. The blood vessels are aligned concurrently, with the vessels that run to the exterior of the body next to the ones that come back from outside. As the warm blood from the inside passes the cooler blood that is coming back from the exterior, it transfers its heat to the adjoining vessel, allowing the great white to keep its interior organs warm [source: Dingerkus]. This movement allows the great white shark to maintain a body temperature as much as 25 degrees Fahrenheit (14 degrees Celsius) warmer than the water [source: Martin].

Being warm-blooded means they can live in slightly colder waters than other sharks, but it also means they need to eat more. Find out what waters the great white swims in on the next page.

The warm-blooded great white lives in fairly temperate waters, and only occasionally in tropical waters because such temperatures might cause the shark to overheat [source: Dingerkus]. The great white shark makes its home all over these waters, from the coastline to the farther offshore locations. They can be seen near the surface or near the bottom of the sea, as far deep as 820 feet (250 meters), but they're rarely seen in the middle of those two extremes [source: Martins, Knickle].

One key element to where the great white makes its home is the abundance of the pinniped; these sharks are usually located near pinniped hangouts, swimming near elephant seals along the California coast or cape fur seals in South Africa.

One place you won't find great white sharks is at your local aquarium, or any aquarium for that matter. While aquarium managers would likely cater to the great white's every need like the finest maitre d's, great whites are nearly impossible to keep in captivity. The Monterey Bay Aquarium was able to keep a juvenile great white for 198 days, breaking the previous record of just 16 days in captivity [source: Carey]. Aquariums have yet to figure out the combination of food, water and tank type that will accommodate the great white, and that assumes that the great white survives the shock of capture and transport. One great white in Australia had to be released because he kept slamming his head into his tank's walls [source: Stevens].

Many biologists want a great white shark in captivity so that we can learn more a­bout them as a species, and of course people want to look in the eyes of the shark that has captivated so many imaginations and eaten so many legs. That's o­ne reason why shark cage diving has become popular recently. People seem to think that if you can't get the sharks to come to you, then it might be time to go to the sharks.

Shark attack survivor Rodney Fox developed the first shark cage, and since then, many adventure seekers have shelled out hundreds of dollars to get an up close glimpse of a great white. As might be expected, this practice has sent up red flags for conservationists and scientists. For example, in order to attract sharks, some companies have sweetened the bait by using cow or pig blood. Scientists worry that these practices will affect the great white's feeding patterns in ways that could eventually pose dangers to humans. Rules that limit the amount of bait and the type of bait used have developed among the diving companies, and there have been no deaths associated with this practice. Still, sharks have gotten their heads stuck between the cage bars, which could potentially break the cage [source: Thomas].

Want to get even more up close and personal with the great white? Turn the page to read about mating and reproduction.

There are several unknowns in the great white shark's reproductive process; biologists have only been able to dissect about 10 pregnant females [source: McGhee]. Because of the scars on their fins, great whites likely practice the typical courtship rituals of a shark, which involve the male biting the female to hold her in place during insemination.

The great white shark is ovoviviparous, which means that the shark grows in an egg, which is then hatched inside the mother. Shortly thereafter, the shark pup is born. While in the womb, great white shark embryos feast on unfertilized eggs, a practice known as oophagy. It doesn't appear that they eat the fertilized eggs, as a few other species of shark has been known to do, but they may swallow their own teeth when they lose them for the calcium [source: Martins, Knickle].

The gestation period is estimated to be 12 to 18 months, but this is largely speculative [sources: McGhee, Francis]. The litter size of the great white ranges from two to 10 pups, although litters of up to 17 pups have been documented [sources: MarineBio, McGhee]. At birth, great white shark pups measure 5 feet (1.5 meters) and weigh about 77 pounds (35 kilograms). The great white grows slowly: Males reach maturity at age 9 or 10, while females are mature at 14 to 16 years of age. Scientists believe that they live about 30 years [source: Martins, Knickle].

Because of the long gestation period, it's possible that female great whites give birth every other year, taking some time to rest after mating. This low reproductive rate and slow growth to maturity are concerns to great white conservationists. Scientists are interested in learning more about the shark's reproductive habits so that they will know better what conservation methods are needed. As we mentioned, great whites face numerous threats from humans, including fishing for fins and teeth and hunting for sport.

Marine biologists lack exact numbers on the great white population, but they're seen very rarely and are currently listed as vulnerable, according to the International Union for Conservation of Nature and Natural Resources. To those who didn't go swimming for a year after "Jaws," worrying about the great white's numbers may seem silly. Wouldn't the world just be better off if these man-eaters weren't around?

Conservationists and scientists stress that a lot of our fear of the great white is in our head, and that these creatures serve an important role in the ecosystem, one example being that they eat seals, which in turn eat salmon. An abundance of seals could lead to the elimination of salmon [source: Martin]. Currently, great white sharks have been afforded protected status in South Africa, Australia and the United States.

To find out more about the great white shark, see the links that follow.

Stuff you need to know:

Now, test your knowledge with these quizzes!

Check out these countdowns!