DNA Analysis Of Tooth Stuck In Surfer's Foot Solves Mystery Of What Bit Him 25 Years Ago


Rachel Baxter

Copy Editor & Staff Writer


The tip of the tooth, shown here next to a dime, was in the man's foot for 24 years, and still yielded DNA results. Kristen Grace/Florida Museum

It’s not every day you pop open a blister to reveal part of a shark’s tooth. But that’s exactly what happened to magazine editor Jeff Weakley last year – 24 years after he was bitten.

In 1994, Jeff was surfing the waves of Florida’s Flagler Beach when he received an unwelcome nip to his foot. The culprit quickly disappeared into the depths and was never identified. But when a tiny chunk of tooth emerged from the blister-like bulge in his foot in 2018, a new opportunity arose to identify Jeff’s foot-munching fish once and for all.


Originally planning to turn the tooth fragment into a stylish pendant, Jeff stumbled upon the story of researchers who identified the species of shark that bit a boy off the coast of New York all thanks to a tooth retrieved from his leg. Intrigued by the prospect of uncovering what bit him, Jeff sent the piece of tooth to scientists at the Florida Program for Shark Research.

"I was very excited to determine the identity of the shark because I'd always been curious," he said in a statement. "I was also a little bit hesitant to send the tooth in because for a minute I thought they would come back and tell me I'd been bitten by a mackerel or a houndfish – something really humiliating."

"It was a mystery waiting for us to uncover," said lab manager Lei Yang, who thought it was “kind of weird” to analyze the tooth but was fascinated all the same. He cleaned the tooth and removed some of the enamel to reveal the pulp tissue within. Comparing the DNA in this tissue to databases of shark and ray genetics, Yang was able to pinpoint the species that bit Jeff – a blacktip – and reported his findings in Wilderness & Environmental Medicine. The majority (70 percent) of shark bite victims never discover which species bit them. 

Blacktip sharks (Carcharhinus limbatus), not to be confused with blacktip reef sharks (Carcharhinus melaopterus), can grow to lengths of 2.4 meters (8 feet). They are found across the globe in warm coastal waters – exactly where beach-going humans like to hang out. However, their diet consists of fish, stingrays, squids, and crustaceans, not people. The fish are sometimes spotted acrobatically leaping out of the water, part of a tactic they use to nab fish shoaling at the surface.


While they’re pretty big, blacktips are generally quite timid. Although they’re known to sometimes show curiosity towards divers, they’re not considered dangerous. The International Shark Attack File reports 28 non-fatal incidences and one death from the species. Those bitten generally end up with a small flesh wound – sharks usually bite humans to check if they're tasty prey, not returning for more once they’ve realized their mistake; a fat juicy seal makes a much better meal than a bony human, after all. The majority of shark-related deaths involve just three species – white, tiger, and bull. 2018 saw four deaths reported worldwide.

Curious but timid, blacktips aren't usually considered dangerous. Michael Bogner/Shutterstock 

Despite his rather painful shark encounter, Jeff remains undeterred by the bite and still enjoys surfing, seeing the threat of a shark bite as no different from the threat posed by a grumpy dog.

"I certainly don't have a hatred of sharks or any feeling of vindictiveness toward them. They're part of our natural world," he said.

An overwhelming majority of human-shark interactions end with a dead shark, not a dead or injured person. Every year, we kill 100 million of the fish, mainly for use in shark fin soup, an Asian delicacy, but also as bycatch and for sport. Blacktips – known to be particularly tasty – are no exception. As top predators, sharks are crucial to the overall health of marine ecosystems; preserving them is paramount.