They're prehistoric, cold-blooded killers, one of the few animals that mankind has not yet conquered and has difficulty dealing with. Perhaps that explains the special status – part fascination, part fear – we accord to sharks.
"Of all the predators implicated in man-eating events, none conjures up more intense dread," wrote author Richard G. Fernicola in his book Twelve Days of Terror.
Whether you agree or not, shark references permeate our culture. We see them in movies, from Jaws to Finding Nemo. We see them on television, where the Discovery Channel airs "Shark Week." We see them on the Internet, where some of the photos depicted here - including one in which a shark comes menacingly close to a kayaker - were viewed by thousands of people as they were spread across the globe via websites and email.
THOMAS PESCHAKThis photo was taken in South Africa, where researchers used kayaks to observe sharks. The photo has been seen by thousands of people as it rocketed around the Internet, proof that the fascination with sharks is universal.
Perhaps more alarming, news desks have elevated man-versus-shark events to primetime, from surfers attacked in California, Florida and Hawaii last week to the shrimp boat captain whose vessel was reportedly sunk by a bull shark in February.
"They say they're endangered species," said Capt. Roger Schmall in a phone interview last month, "but I was the one feeling endangered that day."
Yet relatively little is written about the behavior of sharks and what to do if you actually meet one. Most people know they can sense blood, but are they attracted to metal, bright colors or noise? If you get close, is it better to flee or to be still?
Boaters are undeniably closer to the beast than the rest of the population. Yet the lack of information in boating classes and books – Chapman Piloting and Seamanship, widely considered the boater's bible, has no entry on sharks – results in both mystique and fear that Fernicola captured well.
"Imagine being a shipwrecked sailor, a surfer or a beach bather about to be attacked, dismembered, and consumed by a dark, black-eyed monster with razor-sharp teeth, vicelike jaws, and sandpaper-like skin," he wrote.
What makes sharks more disconcerting than bears or other species that occasionally attack humans, he added, is that the ocean hinders our ability to see the danger coming and to escape from it.
"The shark, on the other hand, is the master predator of its domain," he wrote.
FEAR LIGHTNING, NOT SHARKS
Few experts would dispute that the chances of becoming prey for a shark are so small as to be statistically insignificant.
George Burgess, director of the International Shark Attack File at the University of Florida, says the odds of the average beachgoer drowning in the ocean are one in two million, while the odds of being attacked by a shark are one in 11.5 million. The chance that an attack will be fatal is zero in 264 million.
Put another way, you are literally more likely to be killed by lightning. Between 1959 and 2005, 1,916 people died as the result of lightning strikes in the coastal United States, according to government weather data compiled by researchers at the University of Florida. In that same 46-year period, there were 852 documented shark attacks and 23 resulting deaths.
DisneyAbove, "Bruce" was a parody in the movie Finding Nemo. Below, Jaws broke box office records and sparked a national fear of sharks in 1975. 
Moreover, of the 400 or so species of sharks, only three –white, bull and tiger sharks – are generally associated with human confrontation. Experts say most attacks take place in warmer waters with large human populations, and are often a case of mistaken identity.
Yet fear persists. Roughly 7 out of 10 people who responded to a 2003 survey conducted by the National Aquarium in Baltimore said that sharks were something to be feared.
THE JAWS EFFECT
Most people trace the popular fear and fascination with sharks to the 1975 release of Jaws, the Steven Spielberg thriller that broke all box office records to become the highest-grossing movie of all time (it was toppled two years later by Star Wars).
The movie was based on the novel by the late Peter Benchley, which itself was inspired by much of the American shark lore to be found at that time. A large part of that lore was a string of five attacks – four of them fatal – that took place in just 12 days off the New Jersey coast in 1916. The incidents, chronicled in Fernicola's book Twelve Days of Terror, sparked a media frenzy and widespread public fear.
Earlier this decade, a similar phenomenon took place. The number of shark attacks in the United States dopubled from 24 with no fatalities in 1990 to 53 with two fatalities in 2000, according to the International Shark Attack File at the University of Florida. Though the numbers have fallen in recent years – there were 39 attacks and no fatalities in 2006 – a spike earlier in the decade again sparked media attention and public fear.
In 2000 and 2001, the combined number of attacks increased to include more than 100 attacks and five fatalities, including several gruesome accounts. In one, an 8-year-old boy swimming in shallow water near Pensacola, Florida, was mauled by a bull shark, which bit off his arm. The boy's uncle, who was swimming nearby, wrestled the shark to shore, where it was shot by rangers in order to retrieve the arm, and the boy survived the encounter.
With ghastly true stories like that being reported, and Time Magazine dubbing it the "Summer of the Shark" on its cover, there was little that experts could do to comfort people with statistics or the fact that many shark species are actually endangered.
As Burgess put it, "They are among the few animals left on earth that has an advantage over us."
"˜ALL AROUND THE BOAT'
Indeed, there seems to be a non-stop stream of stories that stoke that fear. Most human-versus-shark encounters now receive some sort of news coverage, which is then amplified as news gets passed on the Internet. Savage imagery – both photos and video – of sharks tearing into boats, kayaks, surfboards and sometimes people is no longer uncommon.
In the last week alone, press accounts detailed several such incidents. A surfer was attacked in Monterey Bay, California, and dragged below the water before re-emerging to be rescued by his friends, with blood gushing from his torso. A boy who encountered a shark while riding on a body board off Oahu in Hawaii was not bit, but kicked the shark's mouth and cut his foot on its teeth in his attempt to escape. In New Smyrna Beach, a stretch of Florida sand famous for attracting both surfers and sharks, two attacks took place, marking the 11th and 12th for that area this year.
On Tuesday, the Associated Press was moved to write about a lifeguard on New York's Coney Island who rescued a small shark washed up on the beach from a menacing crowd of swimmers (yes, it tried to bite him as he swam it out). "The rescue ended a holiday weekend that began with another city shark scare Saturday, when a 5-foot thresher shark washed up on
Rockaway Beach, scaring hundreds of swimmers out of the water," the AP story said.
CAPTAIN HENRY GOREThe shrimp boat Christy Nichole shown listing before it sank. It's captain maintains that a bull shark bit holes in the hull.Of more concern to boaters may be the tale told by Schmall, the veteran shrimp boat captain who says he lost his vessel to a bull shark off the Florida Keys in February.
Most commercial fishermen are familiar with sharks, which often trail their boats to dine on bycatch and other cast off waste. "The sharks are thick out there," Schmall said in a phone interview last month. "They were all around the boat that day."
What happened next was extraordinary by all accounts, and the subject of much speculation. Schmall says a bull shark attacked his boat. Capt. Henry Gore, a longtime friend and fellow shrimp boat skipper who witnessed the sinking, said the creature probably got caught in the propeller. Whatever the exact chain of events, both men say the shark bit huge chunks out of the Christy Nichole, which caused the ship to sink.
When Schmall realized they were sinking, he radioed Gore for help. When Gore arrived about two hours later, he found a shaken crew trying to salvage the ship. Schmall tried to stay aboard and pump out the water as Gore attempted to haul the Christy Nichole to port, but the effort failed. "They abandoned ship and we took 'em home," Gore said in an interview.
CAPTAIN HENRY GOREAnother view of the sinking Christy Nichole. Experts say that shark attacks on boats are rare, but that they do happen.Gore, who shot pictures of the sinking on his cellular phone as he rescued Schmall and his crew, was in awe of the event. "I been at this 20 years," he said, "and I never seen nothing like that."
SHARK VERSUS BOAT
Burgess, who has been investigating shark attacks since the 1950s, said what happened to the Christy Nichole is highly usual and that sharks rarely attack boats. Rather, when it comes to encounters with humans, sharks tend to attack surfers, swimmers and waders – in that order – and even that is exceedingly rare.
"Attacks on boaters fall way back there," he said. "You're going to see shark attacks where you see the most people."
When sharks do attack boats, they are usually Great Whites, who have been known to slam boats and bite hulls or propellars, researchers say. Burgess said Great Whites seem to be attracted to metal and they are often seen near the propellers and dive platforms. Some experts theorize that sharks may be attracted by the electrical field generated by corroding metals below the boat.
The Mote Marine Laboratory in Sarasota, Florida, which studies sharks, has documented white shark attacks on boats in Australia, the United States, Canada and South Africa. According to Mote research, there have been more than a dozen boats attacks in False Bay, just south of Capetown, usually when there was active fishing going on.
A Mote Laboratory wrote in a report on Great Whites revealed one particularly dramatic case in 1977 in which 16-foot shark actually leapt into a 20-foot ski-boat, landing almost squarely on top of the captain, who suffered major injuries. Even in its death throes, the shark thrashed violently and bit through fuel and control lines, eventually clamping down on the gunwale.
GLEN JUSTICEA display at San Francisco's Aquarium of the Bay shows how similar seals and surfers may look to a shark.
Kayakers also tend to be targets for Great Whites. Dan Prather, a Northern California man, was kayaking with friends in July when a shark went after his red boat. He escaped unharmed, but he's got jaw marks on his kayak. Prather declined requests for an interview.
AVOIDING SHARKS
Experts say the best defense against sharks is to learn how they behave and try to avoid them. That starts by staying out of the water in areas with large shark populations, especially at twilight or after dark. Sharks are not nocturnal, but they do often feed at dusk, and they have a competitive sensory advantage after dark.
The International Shark Attack File suggests watching for diving birds or jumping fish, and to avoid swimming in waters that are used heavily by sport and commercial fishermen. Similarly, be aware if you are playing in the water near sandbars or steep drop-offs, where sharks often prowl.
Don't get in the water if you're bleeding or menstruating, because it is true that sharks have an acute sense of smell when it comes to blood. Similarly, try not to wear shiny jewelry, which can look like the sheen of fish scales in reflected light, and avoid bright colors in murky water, because sharks see contrast particularly well.
GLEN JUSTICEMany instituitions cater to the widespread fascination with sharks. At the Aquarium of the Bay in San Francisco, visitors can enter a glass tube where sharks swim around. The facility even rents the space for childrens sleepover birthday parties.
While the best strategy if you see a shark is always going to be to exit the water calmly if you can, the Reefquest Center for Shark Research at the University of British Columbia suggests that, if you cannot exit the water, it may be advantageous to let a shark know you are aware of them. Sharks are ambush predators, meaning like prefer striking without warning.
Remember to take comfort in the statistics–and realized that sharks are in more danger than humans in most cases.
Estimating the world shark population is not an easy business, because they tend to range over great stretches of ocean and are not easily tagged. Scientists at Dalhousie University in Halifax, Nova Scotia, released a report last year showing massive declines in the world's population of deep ocean sharks, including Great Whites and hammerheads, and that North Atlantic sharks seem to be at the biggest risk.
Burgess said sharks have few natural enemies and none larger than man, who kills 40 to 50 million sharks each year through overhunting and other encroachment.
"Compare that to the four or five people killed by sharks worldwide," Burgess said. "I'd say the sharks are under attack, not the people."
Kari Pugh is an editor at Mad Mariner.