Study: Sharks Bite With Upper Jaws

Here's a question you're not likely to ask when you feel that sudden pain in your leg while spending a day in the surf:

How, exactly, does a shark manipulate its jaw so that it can easily rip out a hunk of flesh?

But Cheryl Wilga wanted to know, which is a bit odd since the Aleut Indian grew up in Alaska where concerns over fish are of a more practical nature, like how to catch the elusive king salmon.

Wilga became obsessed with sharks after moving from Kodiak, Alaska, to the University of South Florida in Tampa, where pioneering research was underway to try to decipher just how these mythical creatures function in the water.

Humans More Likely to Nip

It's a big issue in Florida, which leads the world each year in shark attacks on humans. According to the International Shark Attack File maintained by the Florida Museum of Natural History, there were 34 unprovoked shark attacks in Florida's waters last year, contributing to a record number of 79 such attacks worldwide.

Ten of the attacks resulted in fatalities, one of which was in Florida.

But as shark lovers will quickly point out, the chances of getting attacked by a shark are really quite low. You're a thousand times more likely to get bitten by a dog than a shark, according to George H. Burgess, who is director of the International Shark Attack File, a clearing house for all things related to sharks.

In fact, you're 100 times more likely to get bitten by another human than a shark, Burgess says, and much more likely to be killed by lightning.

None of that is likely to ease our fears of being gobbled down by a wild shark, which undoubtedly adds to our fascination with these creatures of the deep.

"Anytime you mention a shark it draws a lot of attention," says Wilga, who recently conducted postdoctoral research on sharks at Harvard University before joining the biology faculty of the University of Rhode Island. She says that's largely because of the fear of shark attacks, but she insists most people think the study of sharks is "cool."

But it's not easy.

"Sharks are a pain in the neck to work with," she says. "They have to have a lot of tender loving care."

Many species cannot survive in captivity, even for a little while, and those that do require a big tank, and lots of clean water, and there's the little problem of "you always know they can potentially remove parts of your body," Wilga says.

Her research has led to a better understanding of two key areas — how the shark's jaw functions, and how the fish maintains its buoyancy in the water. Both areas have yielded some surprises, but it took a marriage of physics, engineering and biology to find them.

Because of the difficulty of keeping sharks in the lab, Wilga's research has been focused on smaller sharks that pose no real threat to humans, including the spiny dogfish, sandbar and bamboo sharks. It is thought that many characteristics of these species are shared by all sharks.

Upper Jaw Clamp

At the University of South Florida, Wilga worked with Philip Motta, a biologist who moved shark research beyond the realm of studying cadavers and trying to figure out how they function.

It was while working with Motta that she made her first breakthrough. Many experts had through that sharks bit their prey by maneuvering their lower jaw, like humans, but that turned out not to be the case.

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