Myths and statistics about the oceans' most fearsome creature
by David Johnson
Sharks are not bloodthirsty maniacal killers. As the ocean's number one predator, sharks help maintain the balance of nature by reducing animal populations.
Twelve Deaths in 2011
Considering that tens of thousands of people come in close contact with sharks each year while swimming, surfing, or boating, the number of shark attacks is negligible. In 2011, there were 75 confirmed "unprovoked" shark attacks in the world, resulting in 12 deaths.*
The actual number of attacks is hard to determine because of poor reporting in many areas. News about shark attacks is often supressed so tourists will not be driven away.
Most shark attacks occur on the inshore side of a sandbar or between sandbars because fish congregate there and because sharks can become trapped at low tide. Sharp drop-offs also attract lots of fish and, therefore, sharks.
Hit and Run
The most common type of attack is the so-called "hit and run" assault. The shark bites and then quickly releases the person and disappears. These attacks usually involve injuries to the leg below the knee and are not usually fatal. Humans are usually considered too bony to be a good meal for a shark.
Hit-and-run attacks are probably most often cases of mistaken identity. They usually happen near the surface and in poor visibility. Breaking surf, heavy currents, and other factors may make it hard for the shark to see its victim clearly.
Surfboards and Seals
Seen from below, swimmers or surfboarders are often mistaken for seals or sea lions, whose fatty bodies are a favorite treat for sharks. Human splashing creates irregular ripples in the water below, which to a shark may indicate an injured seal or fish, that likely be an easy meal.
Shiny jewelry that gleams like fish scales, multi-color swimsuits, and irregular tanning, especially on the bottom of the feet, could also confuse a shark into thinking a person was an animal.
In some hit-and-run attacks, sharks could be displaying dominance behavior, perhaps warning a human that it is intruding in its territory.
When attacks are reported, it is often difficult to determine what type of shark was involved since even experts can have trouble distinguishing them when in the water.
In Florida waters, black tip, black nose, and spinner sharks are probably responsible for most of the hit-and-run attacks.
"Bump and bite" and sneak attacks are much more rare and more apt to result in serious injury or fatality. These incidents usually take place in deeper water and are not believed to be cases of mistaken identity. Rather, sharks are angry or want to eat.
In bump-and-bite attacks, the shark circles its victim then bumps into it before attacking. Sneak attacks occur without warning. Often, these attacks are repeated several times.
Fearsome Great White Shark
White, tiger, and bull sharks are believed responsible for most bump-and-bite and sneak attacks on humans. These are the largest species that eat human-size prey, including marine mammals, sea turtles, and large fish.
Gray reef, lemon, dusky, blue, sand tiger, nurse, and Ganges River sharks will also attack humans.
Still, of the more than 375 species in the world only about 30 have ever been reported to even have attacked humans. In fact the largest species, the whale and basking sharks, eat only plankton.
Even so, experts warn that any shark six feet long or more is large and powerful enough to kill a person and should be treated with caution.
Provoked attacks are most common when a person touches a shark, including helping untangle it from fishing nets. Divers who touch or feed a shark risk attack.
*Statistics are from the International Shark Attack File, maintained by the Florida Museum of Natural History at the University of Florida, Gainesville, and the American Elasmobranch Society.
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