Hammerschlag has made headlines around the world for his research on sharks. In 2009, he published a paper about the hunting strategies of great whites. While watching sharks devour Cape fur seals, he realized the attacks weren't as random as commonly thought. Instead, older sharks acted like underwater assassins, learning the best hiding spots and carefully positioning themselves deep enough to develop the speed necessary to hit the surface and catch unsuspecting seals.
Last year, Hammerschlag hosted a "Summit at Sea" for celebrities including Sir Richard Branson. Also in 2010, he received death threats after defending the bull sharks that devoured 38-year-old Stephen Schafer while Schafer was kiteboarding near Stuart. Though there were 11-inch chunks torn from Schafer's thighs and buttocks, Hammerschlag told newspapers that "deadly shark attacks are very rare" and that the fish "usually don't bite people unless provoked."
"I wince every time there is an attack," he says now. "It's never good, for sharks or for people."
Hammerschlag's efforts to protect sharks have also made him enemies among local shark fishermen, including Boehm. Last year, the shark hunter unexpectedly phoned Hammerschlag to say he had found a shark tag belonging to the scientist. Then Boehm asked him how much he would pay for it, Hammerschlag says.
When Hammerschlag hesitated, Boehm hung up, but not without delivering a warning first: "I'm going to throw the tag up in the air and shoot it."
That was before the shark snuff video surfaced. Now Hammerschlag is incensed.
"I don't want to start a war against commercial shark fishermen," he says. "But the guy on the video is proud of himself. It doesn't look like they are doing this to make a living. They aren't just following orders. They are clearly getting enjoyment out of seeing these animals in distress."
Hammerschlag doesn't apologize for his affinity for sharks. Rather, his eyes light up when he's asked about his latest research. Great white sharks' teeth are loosely set in their jaws, he explains intently. They have their own nerves and blood supply, "almost like fingertips."
"They can splay them out like a cat's claws," Hammerschlag says, "and use them to gather information about objects."
Sometimes that object is a person, he admits. But even among notoriously deadly great whites, more than 90 percent of attacks aren't fatal.
"I've seen thousands of attacks on seals," Hammerschlag says. "They are brief, vertical attacks... Within seconds there is nothing left. If a white shark wanted to eat you, it could. There's nothing easier than catching a 150-pound monkey swimming in the water," he adds wryly. "They are two-ton killing machines. But there are people who have been quote-unquote attacked by a great white, with their head in its jaws, and had nothing to show for it but a couple of stitches.
"What does that tell you?" he asks. "They didn't survive because of their bravery. That was the shark's decision."
Anthony Segrich isn't so sympathetic. Since his run-in with the shark April 26, he has spent the past month in a tiny corner room at St. Mary's Medical Center in West Palm Beach. For hours every day, he cradles what looks like a small lunch cooler. A fine tube of blood runs from the contraption to Segrich's swollen, cast-covered leg.
"It's my wound vac," the Luke Wilson look-alike says with a hint of pride. "I call it my chum bucket. It's what they use in Iraq and Afghanistan nowadays to rebuild muscle tissue."
Like a war veteran, Segrich will likely be haunted by the attack for years to come. But for now, he seems strangely well-adjusted for someone who lost half his blood — and nearly his leg — by the time he arrived at the hospital. "I don't know if you're squeamish," he adds, taking out his iPhone, "but I pretty much filmed the whole thing."
Segrich shows video of the 13-inch bite marks on his left leg and the cavernous hole where his calf used to be. "It was pretty chunky at first," he says. That was before three operations, 126 stitches, and a skin graft.
Then he pulls up underwater footage a friend shot while spearfishing with Segrich. A loaded spear gun looms in the foreground. Just ahead of Segrich, a cluster of cobia shifts back and forth in the ocean current. And in the background: the unmistakable silhouettes of a half-dozen sharks, patiently circling, waiting for blood.