July 6, 2011  -- A small shark that's as nasty as it is fearless, attacking everything from Navy submarines to killer whales, has been blamed for its first clearly documented attack on a live human being.

A so-called cookiecutter shark, which was probably a little more than a foot long, took a chunk out of the leg of a distance swimmer who was trying to make a nighttime swim from the island of Hawaii to Maui.

The attack occurred 90 minutes after sunset March 16, 2009, but has just recently been documented by scientists in Hawaii and Florida.

Despite their reputation, sharks historically have not posed a widespread danger to people. Only two other cases involving attacks on humans by cookiecutter sharks have been widely accepted by experts, but both those attacks were on human cadavers, one a drowning victim and the other a suicide.

While this is the best evidence yet for attacks on live humans, there are several other cases that are highly suspicious.

So, are we in for another Jaws? Maybe not, because the cookiecutter shark, so named because it gouges horrific pockets of flesh from its prey, feeds at night in deep tropical waters where it is not likely to encounter humans.

But this case is so spooky that the director of the International Shark Attack File at the Florida Museum of Natural History thinks people ought to at least be aware the nature of this predator.

"It's not as scary as 'Jaws,' but it's very different from any other kind of attack we have [in the file] because of the size of the shark and the modus operandi," George Burgess, director of the file, said in releasing the study.

It is to be published in an upcoming edition of the journal Pacific Science.

The shark is a master of the hit, rip and run technique. It likes deep waters and has been documented swimming as deep as 2.3 miles. But when the sun goes down, it moves up through the water column, searching for prey. Anything will do, as apparently it fears no one.

It likes a moonlit night, and it usually approaches its target from below, literally sucking up to the prey by attaching itself with suction from its fleshy lips. It sinks its hook-like upper teeth and then its "proportionally massive lower teeth" into its victim. Then it twists sharply, gouging out a chunk of meat much like a cookie cutter. Or as some scientists believe, like one of those tools used to carve out melon balls.

While the shark doesn't get any bigger than 20 to 22 inches, size doesn't matter in its kingdom. It has been known to attack northern elephant seals, whale sharks, leopard seals, killer whales and, yes, even submarines, according to the study.

The Navy had to replace rubber seals and coatings on many of its subs after cookiecutters chomped holes in them.

And now, perhaps, it has developed a taste for humans.

No one knows that better than Mike Spalding of Maui. In March of 2009, Spalding, then 61, waded into the water off Upolu Point to try to swim across Alenuihaha Channel to Maui. He was accompanied by a 30-foot escort vessel, the Radon, and a kayak.

Shortly before 10 p.m., it had become so dark that the Radon skipper turned on his night lights. A little later he asked the person in the kayak to turn on lights as well. The bright lights probably attracted squid toward the surface, a common prey for the shark.

Cookiecutter Sharks Travel in Packs

"About 10 minutes after the kayak's bow light was turned on, the victim was bumped by a squid," the study says. "Over the next 20 minutes he was bumped by squid two or three more times in the shoulder and side areas at irregular intervals."

At 10:03, Spalding felt a very sharp pain on his lower chest. "The sensation was instantaneous and localized, like a pin prick, and felt like a bite from a small mouth. The victim yelped and swam over to the kayak."

Less than 15 seconds later, while he was trying to crawl aboard the kayak, the shark hit his left calf. It took a chunk of flesh that was later estimated to be four inches wide and at least an inch and a half deep.

Spalding was rushed to Maui Memorial Hospital, where his doctor, Peter Galpin, a co-author of the study, began treatment. A skin graft was "harvested" from Spalding's left thigh and used to close the open wound.

It took nine months for it to heal.

While Spalding is the best documented victim of a cookiecutter shark attack, the incident has fueled concerns expressed during the years by other scientists, because while this shark is -- fortunately -- a little fish, it travels in schools and is suspected of at least two mob attacks.

In the 1980s, an underwater photographer was "attacked by a swarm of small sharks" and his wounds resembled the scars that have been found in many marine animals that were clearly the work of cookiecutters.

And a 1955 report told of a shipwrecked crew in the mid-Atlantic, just north of the equator, who "were greatly bothered by the attacks of an extremely ferocious small fish less than a foot long and blunt nosed. These small fish swam in schools and were very persistent. The bites were clean cut and upwards of an inch or more deep."

But these are rare cases, and usually happen at night far from shore in tropical waters, where humans rarely swim. On the other hand, the study notes that the shark's "hit and run feeding behavior" is a little troubling.

The cookiecutter doesn't spend a lot of time analyzing the situation and it has no fear of larger creatures, so a human swimmer might just be a "novel potential prey item" for the shark.

The scientists suggest that special care should be taken when swimming at night in tropical waters "near man-made illumination, during periods of bright moonlight, or in the presence of bioluminescent organisms."