100. Between 30 and 80 percent of a shark's flesh is made of water. A protein network gives the flesh its structure.
99. One of the Lord Mayors of London was a shark attack victim in 1749. Brook Watson lost his leg in an attack while docked off the coast of Cuba.
98. Shark teeth are popular and often inexpensive beach souvenirs. Sharks shed their teeth constantly, and once one falls to the ocean floor, it's quickly covered with sand. It soaks up sediments like silica and calcite, which change the tooth's color from white to gray or brown.
97. Of the average 30 to 50 shark attacks reported each year, only 5 to 10 prove to be fatal. So while being bitten by a shark is rare, dying from a shark bite is even rarer.
96. As sensational as shark attacks are in newspaper headlines, the reality is that you're more likely to be bitten by another person than a shark.
95. While many people fear sharks and think of them as one of the world's most aggressive and deadly animals, the chances of dying from a shark attack fall well below the chances of being killed by hornets, wasps, bees or dogs.
94. A few of the known shark species will drown if they stop moving. Great white, mako and salmon sharks don't have the muscles they need to pump water through their mouth and over their gills. As long as they keep swimming, water keeps moving over their gills, keeping them alive.
93. Overfishing can have a dangerous effect on sharks. The whale shark, for example, has to live to be 30 years old before it can reproduce, and its life span lasts between 60 and 100 years. As a result, it can't reproduce fast enough to keep up with fishing demand.
92. From 1580 to 2007, there were a reported 64 fatal great white shark attacks. Sharks haven't fared as well: When you count every species, millions of sharks are killed by humans every year.
91. Sharks' livers contain lots of oil. This makes the liver a relatively buoyant organ, which helps sharks keep their balance in the water.
Top 100 Shark Facts: 90-81
90. Although it's heavily fictionalized, the film Jaws was based on a real incident in 1916, in which four people were killed by a shark off the New Jersey coastline.
89. A common myth is that sharks don't attack in the middle of the day. And that may be true — but it's likely because most beachgoers get out of the water to rest or eat at lunchtime, so there aren't as many people around to cross paths with sharks. Sharks don't follow the same three meals-a-day eating schedule as humans, they eat when they find food, no matter what time it is.
88. Headed to shark-filled waters? Pack your boxing gloves. Punching a shark in the nose or poking its eyes can help to fend it off during an attack. Aim for the sensitive eyes or gills — or, if your aim is off, the much bigger target of the snout. Most sharks don't want to work that hard for their food and will swim away.
87. Surfers are more likely to die from drowning than from a shark attack, but it is true that great whites can be confused and intrigued by the shape of a surfboard. From beneath the surface, a great white might mistake the board's outline for that of a seal, walrus or sea lion.
86. Almost all sharks like to do their hunting solo, but scalloped hammerhead sharks prefer to travel in schools during their summer migration.
85. Tiger sharks, great white sharks and bull sharks are behind most shark attacks on humans. These species live almost everywhere, are large enough that their prey is human size, are powerful enough to inflict a fatal bite and are at the top of the food chain, so they aren't afraid to attack.
84. Sharks may seem like a permanent part of the ocean, but according to the World Conservation Union, 20 percent of sharks are close to extinction. The main culprit? Commercial fisheries accidentally catching sharks on their hooks and nets.
83. In the extremely rare event that a shark bites you, it probably won't take a second taste. In attacks on humans, sharks typically bite, hold on for a few seconds and then let go once they realize they're not tasting a sea creature.
82. Sharks that eat their siblings' eggs in the womb aren't vicious. They're just seeking out nutrients to sustain themselves as they grow.
81. Martha's Vineyard and Nantucket Island were inspirations for the fictional town of Amity Island in Steven Spielberg's 1975 thriller Jaws. The movie may have contributed to a decline in beach attendance in the late 1970s, even though great white sharks are said to be uncommon in northeastern waters.
Top 100 Shark Facts: 80-71
80. Great white sharks eat 11 tons of food a year! Compare that to a human being: Each of us eats closer to half a ton of food every year.
79. Think you have to be swimming in the ocean to meet a shark? Think again. Bull sharks have a fondness for freshwater. They've been spotted in bays, lagoons and even rivers, sometimes thousands of miles inland.
78. Most species of shark can be found in open water, allowing them plenty of space to swim and fish to eat. However, the goblin shark lives along outer continental shelves and underwater mountain ranges. Their dwellings are too deep for humans, so we don't know much about them.
77. For tiger shark moms-to-be, two different uteri are the key to giving birth to at least two pups.
76. Whale sharks are the world's biggest fish — and they have big families, too. One whale shark can give birth to 300 live shark pups in one litter.
75. Blue sharks are among the most threatened species of sharks in the world. Trade in shark fins and overfishing have caused them to decline so rapidly that scientists worry about their future recovery.
74. Until recently, sharks were thought to be immune to cancer. However, recent research proves otherwise.
73. Most shark attacks on humans occur within a few hundred yards of shore. That's not because sharks stick to this part of the sea ... it's just where people are more likely to be.
72. How do you study sharks in the wild? One way is through tracking devices that send constant updates to researchers. The Smart Position-Only Tag (SPOT) records sharks' activities and transmits data to a satellite. Pop-Up Archival Tags (PAT) record details of the shark's environment, popping off the shark at a preprogrammed time.
71. The frilled shark's circular mouth, filled with more than 300 spiny teeth, earns it the nickname of the modern Loch Ness monster. You won't find it near Scotland, though; it calls the oceans around Japan, New Zealand and Africa home.
Top 100 Shark Facts: 70-61
70. Most sharks live in saltwater, so how do river sharks survive in freshwater? They take in extra water and then urinate into the stream around them, at a rate over 20 times faster than the average saltwater shark!
69. What's older than sharks? Almost nothing. Sharks have been swimming in the ocean for more than 400 million years. They predate practically everything that has a spine, including humans and dinosaurs.
68. Shark fin soup is a delicacy in China and is served at important events, like weddings and anniversaries. When dried, the fins take on a texture and shape similar to noodles. According to tradition, longer noodles mean a longer life when you eat them. There's a downside, though — finning leads to the deaths of 73 million sharks every year.
67. Exactly how a shark comes into the world depends on its species. Some, such as horn sharks, hatch from egg cases called "mermaid's purses." These tough, leathery pouches protect the eggs while the sharks are growing.
66. You'd need a lot more than just a bigger boat to track down the shark responsible for a particular attack. Unlike what you saw in Jaws, sharks can travel hundreds of miles in a day, so it doesn't take them long to leave the scene.
65. You may have heard that the pliable cartilage in a shark's skeleton is a potent cancer fighter. However, scientists have found that over-the-counter pills containing shark cartilage don't reduce the growth of tumors, and their side effects can include making you sick to your stomach. Researchers are still studying the molecules that make up shark cartilage for future use in medicine.
64. You may think of sharks as ravenous, man-eating terrors of the sea, but in reality, only 20 of the more than 350 species of shark — a small minority — are known to attack humans.
63. Shark attacks occur around California because U.S. government protection of sea mammals, like seals, sea lions and sea otters, has increased their populations off the West Coast. There's more food for sharks there, and humans just get in the way.
62. While many of us have learned to fear sharks, they're the ones who should fear us. People are sharks' biggest predator. In fact, humans kill more than 73 million sharks annually.
61. Sound waves travel fast and far in water, so sharks have no trouble picking up low-pitched noises from movements such as fish schools, swimmers and even Coast Guard helicopters flying low over the ocean.
Top 100 Shark Facts: 60-51
60. Humans are the shark's biggest predator, but killer whales, crocodiles and seals have been known to eat sharks as well. Large sharks will even go after smaller, younger sharks that might make easy prey.
59. Even though sharks have rows and rows of razor-sharp teeth, they don't use their pearly whites to chew their prey. Shark teeth are strictly for ripping, and the resulting chunks are swallowed whole.
58. Contrary to popular belief, sharks aren't color blind. Divers have claimed for years that sharks are attracted to certain colors, such as the "yummy yellow" of some wetsuits. While color preference hasn't been proven, scientists know that some sharks that live in well-lit environments have developed cones cells that are just like the ones humans use to distinguish colors.
57. The prehistoric shark Megalodon probably grew to 60 feet (18 meters), and it's popularized today as the largest shark ever to exist. However, there was another plated fish called the Dunkleosteus, which, though not a shark, weighed in at around 4 tons. If they'd lived during the same era, Dunkleosteus could have proved to be a deadly match for the Megaladon.
56. Sharks' skeletons are made entirely of cartilage, an elastic tissue that is much softer than bones. When a shark dies, salt from the ocean water completely dissolves its skeleton, leaving only the shark's teeth behind.
55. Galeophobia is the excessive fear of sharks. It comes from the Greek word "galeos," which was a particular type of shark.
54. Be glad you're not a shark, moms! The gestation period for a pregnant female shark can range anywhere from five months to two years.
53. Sharks can generate up to 40,000 pounds per square inch of pressure in a single bite. That's easily enough to chomp a meaty limb right off.
52. The dangerous act of swimming in cold water can actually boost the odds of survival for a shark attack victim. The cold water causes your body temperature to drop. You'll be at risk for hypothermia, but your blood loss will slow down, buying you some time for rescue.
51. Sharks' eyes are on the sides of their heads, so they have an amazingly wide sightline spanning nearly 360 degrees. Their panoramic view of the undersea world is inhibited only by two blind spots, one in front of the snout and the other directly behind the head.
Top 100 Shark Facts: 50-41
50. Great hammerhead sharks are nomadic and have been known to roam all the way from the coasts of Florida to polar regions. This aquatic globetrotting lets them take advantage of rising and falling water temperatures.
49. While the word "shark" may conjure up images of great whites and hammerheads, there are at least 350 shark species roaming the world's oceans today. They vary in size and even shape, but they all tend to share similar body characteristics like large livers, flexible cartilaginous skeletons and enhanced sensory systems.
48. It takes a lot of work to maintain a gene pool: Some female sharks use sperm from multiple males to father a single litter. That makes her pups half-siblings, even though they're born at the same time.
47. Angel sharks, also known as sand devils, will dig themselves into piles of sand. They lie in wait, waiting for unsuspecting fish to pass by before rising up and attacking.
46. Jaws is considered to be the godfather of all shark movies, but six years before the Steven Spielberg blockbuster, Burt Reynolds got into a wet suit to star in Shark. Real sharks were used throughout the movie, and a stuntman was killed filming a scene with the predators.
45. Whale sharks are three times larger than the average shark, but don't be afraid of these docile creatures. They are filter feeders that use their many rows of teeth to gather plankton, making them great diving companions for eco-tourists.
44. The size of a shark species relates to where they hunt: Smaller sharks tend to feed near the ocean floor, and larger sharks hunt in the middle depths and near the surface, where they can more easily snatch larger prey such as seals.
43. Some sharks start working before they're even born, chewing their way out of their egg to enter the open ocean.
42. The Aztecs attached strings of chili peppers to their canoes to keep sharks away, a practice that modern day scientists doubt was actually effective.
41. Reef sharks number among the shark species that have to keep moving so they can breathe. But in the 1970s, scientists discovered a place called the Cave of Sleeping Sharks near Mexico, where reef sharks could lie motionless. High levels of oxygen and low levels of salt in the water keep the sharks alive.
Top 100 Shark Facts: 40-31
40. The Aztecs had a mysterious mastery over sharks. In 1978, archaeologists uncovered remnants of shark bodies under the ruins of the Aztec Great Temple. The sharks were likely used as a sacrifice to the gods.
39. Recreational shark fishing, which has become a large threat to the shark population, wasn't popular until 1975. After the premiere of Jaws, people wanted to snag a "man-eating" great white.
38. Blue sharks are piggy eaters. They'll keep eating until they regurgitate, after which they go back to eating!
37. Like lions on land, sharks are at the top of the food chain in the underwater jungle, and their eating habits affect the populations of all sea life below them. Without large sharks, octopus populations would jump, which would then decrease the number of lobsters, since they are one of the octopus' favorite snacks.
36. Sharks hunt for food, not for sport, but they follow the same habits as serial killers do. When on the hunt, both tend to stalk their victims, staying far enough away to be hidden, but close enough to strike when the opportunity arises.
35. Electroreception allows sharks to notice the smallest changes in the electricity conducted through saltwater. Blood in the water changes its conductivity. So, sharks don't see blood and attack: They sense and smell it.
34. Instead of closing its eyelids, a great white shark rolls its eyes into the back of its head when it attacks. This behavior helps the shark protect its eyes from debris and the thrashing of its prey.
33. It's possible that shark repellants could come from an unlikely source: magnets. Magnets in the water can interfere with a shark's electroreception. Don't just strap on some magnets and head to the beach, though. With current technology, sharks have to get very close to the magnets before they're affected.
32. If a shark sinks its teeth into your arms during a shark attack, your best bet is to latch on to the shark. Sharks like to whip their prey around in order to break off chunks of meat, so the closer you stay to the shark, the better your chance of keeping your limb.
31. Turkish car designer Kazim Doku designed a concept car modeled after the body of a shark. It's a hovercraft — after all, sharks glide through the water and don't clunk around on land — that won Audi and Milan's Domus Academy's 2008 Desire Design Competition.
Top 100 Shark Facts: 30-21
30. Sharks can use heartbeats to track their prey. Sharks have nodules on their noses about the size of a pimple, called ampullae of Lorenzini. These nodules sense electricity, so the electrical pulses that come from a beating heart can act like a beacon for nearby sharks.
29. You can't see a shark's ears, but that doesn't stop it from being able to hear you from more than two football fields away. That's because sharks only have inner ears, which they use to track the sound of their prey from lengths of more than 800 feet (244 meters).
28. If you're watching a circling shark and wondering if it's about to attack its prey, here are the clues: The shark will hunch its back, lower its pectoral fins (the ones near its belly) and swim in zigzag motions.
27. Unlike humans, whose upper jaw is a fixed part of the skull, a shark can dislocate and protrude its upper jaw to help it grab and hang onto prey. Talk about a big-mouth!
26. Jaws wasn't the first time sharks have been given a bad rap. Ancient Greek historian Herodotus claimed that a group of sharks destroyed a Persian fleet in the 5th century B.C., which may have been the first time sharks were tagged with a killer reputation.
25. Sharks have an astounding sense of smell, so powerful that they can detect a single drop of blood in an Olympic-sized pool.
24. Different species of sharks have their own set of etiquette during a feeding frenzy, a rare occurrence when a large group of sharks all go after the same prey. Caribbean reef sharks, for example, follow a distinct pecking order in which the biggest shark eats first.
23. Sharks can see in murky water because of a special feature that makes their eyes more sensitive to light. A membrane in the back of the eye called the tapetum lucidum reflects sunlight back into the eye, so the shark can make more use of what little light is there.
22. Mile for mile, Volusia County, Fla., has more shark attacks than anywhere else in the world. Because the area boasts so many swimmers, these waters have seen 210 attacks since 1882. Most of the attacks are just bites, though, so they don't keep die-hard surfers and swimmers away.
21. Great white sharks are picky eaters. Their diet requires lots of fat, and after one bite a great white shark can determine whether or not the meal will satisfy its nutritional needs. If it doesn't, the shark will leave the rest and swim away.
Top 100 Shark Facts: 20-11
20. The megamouth shark wasn't discovered by scientists until 1976, and there have only been 41 known sightings of the species. Like whale sharks, the megamouths are filter-feeders and have huge jaws that extend past their eyes.
19. Sharks have quite a few more senses than humans do. One comes from lateral line organs, which act like an internal barometer. When solid objects glide through the water, they create waves of pressure that a shark can feel with the sensitivity of a physical touch. By sensing these pressure waves, a shark can detect both the movement and direction of the object!
18. Not all sharks are easily identifiable as predators, especially the cookiecutter shark, which can camouflage itself. The shark's underside glows, with the exception of a small strip on its neck that looks like a much smaller fish. Predators mistake this strip for a snack, and the cookiecutter takes a bite of their flesh before swimming away.
17. If the whale shark is the largest species, then pygmy sharks are among the tiniest! They measure an average of 8 inches (20 centimeters) in length and the can make their own light, a phenomenon that's especially helpful as pygmy sharks will dive more than a mile underwater to hunt.
16. In 2009, spear fisherman Craig Clasen stabbed a tiger shark after it charged his friend off the coast of Louisiana. The stab aggravated the animal, which then went after Clasen. After a two-hour struggle, Clasen finally killed the shark and took a symbolic bite of his catch, staying true to his promise always to use any animal he killed.
15. Did you know sharks move like airplanes? A shark creates forward movement by moving its tail, which acts like a propeller. As the shark moves forward, water moves over its fins as though they were wings, creating lift.
14. Have you ever been hungry enough to eat a horse? How about a spare tire? Researchers have discovered common objects, like tires, gasoline tanks and license plates, left in one piece inside the stomachs of tiger sharks.
13. If you're so inclined, you can track both sharks and serial killers using an investigative technique called geographic profiling, which pinpoints locations where attacks are likely to happen. In great whites, those locations are other animals' travel routes and landmarks like reefs and channels.
12. Hammerhead sharks may look like the victims of an evolutionary blunder, but their oddly shaped heads, called cephalofoils, really make them better hunters. The electrical sensors the sharks use to pinpoint their prey are spread out along the cephalofoil's wide surface area, giving them better prey detection skills.
11. Sharks are especially susceptible to the moon's control of ocean tides. The phase of the moon can affect sharks' eating habits and draw them closer to shore ... which in turn, can lead to increased attacks on humans.
Top 100 Shark Facts: 10-1
10. The average shark lives to be 25 years old, but some can get as old as 100! They live so long because their chances of contracting a disease are low. Their skeleton is made up entirely of cartilage, which drastically lowers the likelihood of developing a tumor and strengthens their immunity.
9. Modern sharks breathe by ram ventilation, a process that forces water into their mouths and then processes it as they swim forward. When they're idle, sharks use muscles around the mouth to pull water in and over their gills. Sharks that don't have muscles strong enough to do the job must take shorter and less frequent rest stops.
8. One of the worst shark attacks in history was the sinking of the USS Indianapolis during World War II. Nearly 900 sailors were stranded in the Philippine Sea near Guam for four days. Experts can't be sure how many sailors lost their lives to sharks, but when help arrived, only 316 people were still alive.
7. A shark's tooth-shaped scales, called denticles, allow it to move swiftly through the water without collecting barnacles and algae deposits on the skin. In 2005, engineers successfully mimicked the pattern of scales, creating a bacteria-resistant coating.
6. It's a shark-eat-shark world ... sometimes even before the sharks are born. When some species' embryos begin to develop teeth, they eat their unborn brothers and sisters until one shark remains, an act known as intrauterine cannibalism.
5. Sharks respond to a sound known as a "yummy hum." It's not an actual hum, though. It's an infrasonic sound (one that's too low for humans to hear) that injured fish make, drawing sharks to an easy meal.
4. Almost 50 different species of sharks have light-emitting organs called photospheres. Sharks use the light that comes from these organs for camouflage and to attract mates.
3. Every once in a while, a female shark can reproduce without any contact from a male, an act known as parthenogenesis. Scientists have only documented a couple of cases of parthenogenesis, but some suspect that just about any female shark can get pregnant on her own in the right circumstances.
2. Sharks living in frigid waters can heat their eyes using a special organ next to a muscle in their eye socket. This ability enables them to keep hunting their prey in extreme temperatures.
1. "Jumping the shark" is the kiss of death when it hits our favorite sitcom, but it's just as deadly in the real world. Great white sharks off the coast of Seal Island, Africa, are known to jump almost 10 feet (3 meters) in the air to catch unsuspecting seals ... or anything else, for that matter.