The Science of Shark Attacks and How to Avoid Them

Despite two highly publicized shark attacks last month along the U.S. coast, at least one scientist says it's safe to go back in the water.

In fact, he points out that you're actually in more danger on the way to the beach.

"There are millions of people in the water at any given moment of the day," said John McEachran of Texas A&M University. "When you consider all of the people in the water at the same time, the number of shark attacks is very, very remote."

Every year across the globe, nearly one million people die in automobile accidents. More than 42,000 of those deaths occur in the United States.

Shark attacks resulting in deaths occur much less frequently than car wrecks, but they get much more publicity.

"Shark attacks are like airplane crashes," said McEachran. "The vast majority of airplane trips are safe, but when a crash occurs, it gets big headlines."

According to the International Shark Attack File, in 2004 there were only seven shark related deaths worldwide. That number was even smaller in 2003 and 2002, when four and three deaths were recorded respectively.

Should you get to the beach safely, there are still plenty of bigger risks to your health than a shark attack.

"A greater percentage of beachgoers are injured by jellyfish, stingrays, or hardhead and gafftop fishes, which have poisonous spines," McEachran said. "They are more likely to cause harm than a shark."

Even peanuts, McEachran says, are a greater threat to humans than sharks. About 90 people die worldwide each year from allergic reactions to eating peanuts.

There's a better chance you'll win the lottery than be bitten by a shark. [Other Odds of Death]

You're not dinner

Should you be bitten by a shark, it's not just bad luck for you. Sharks don't really like eating humans. They'd rather snack on a seal or sea lion – something with higher fat and energy content. We're too bony.

"Sharks don't eat humans," shark exert Peter Kimley of the University of California, Davis told LiveScience. "They spit out humans. Humans aren't nutritious enough to be worth the effort."

But most sharks don't have very good vision, and sometimes objects like buoys and people look similar to a seal – a shark's favorite meal.

 "A human being of course, close to the surface, does a pretty good job looking like a seal, and one on a surfboard does an even better job," George Burgess, curator of the International Shark Attack File told LiveScience. "It's not like they're out there saying ?let's try to find a human today.'"

Most often, sharks spit people out after carrying them underwater for a ways. Because their eyesight isn't very good, they need to feel objects over with their mouths to decide whether they want to eat them or not.

Humans are usually spat out. Unfortunately, by that time they've either drowned or have bled to death.

How to avoid a shark

The best thing to do when you see a shark is move away, experts say. Move swiftly but calmly – sharks are attracted to splashing. If the shark is already swimming at you, no need to go quietly. Just get away.

If a shark bites you, try to get away before it takes you under for too long. Hit it on the snout, head, and eyes, and it may let you go.

Not all the blame for shark attacks falls on the beasts.

Attacks are more frequent in summer months, Burgess said, because "both sharks and humans have seasons where they want to be in the water at the same time."

Sometimes sharks bite because people provoke them, either by putting food in the water or grabbing one as it swims by. Other times, it's just because someone is in the wrong place at the wrong time. Surfers often unknowingly put themselves in one of these wrong places. The good breaks they crowd around are often created by seamounts on the ocean floor, which are popular feeding areas for sharks.

While the number of shark attacks and deaths is still much lower than car wrecks, attacks have been climbing steadily.

"Decade to decade you find that the number of shark attacks has continued to rise," Burgess said. "This is largely because the human population and interest in water activities has grown."

So what's the prudent course?

"If you use some good common sense in the water, you should be fine," said McEachran. "To put your mind at ease, go to a beach that has lifeguards. They should be looking for possible sharks."

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Back in the Water?

"We swam every year at the ocean -- never been afraid of sharks like we are now. We're beach lovers. We can't stay away. We're just a lot more cautious now."

-- Celia Page, a teacher from Waycross, Ga., who was in the water with her 3-year-old daughter last week after two shark attacks along the Gulf Coast left one teen dead and another with a severed leg.

"We're still going to have a nice vacation but I don't really think I'll get back in the Gulf or the ocean again. It's their domain out there."

-- Heather Black, of Owensboro, Ky., who was visiting Cape San Blas, Fla. with her husband last week.

-- Associated Press

By the Numbers

Unprovoked shark attacks worldwide in recent years:

Shark attackes by species since the year 1,580:

Credit: International Shark Attack File

Image Gallery

Great White Sharks