When Jeff Weakley found a 24-year-old piece of shark’s tooth in a blister on his toe last summer, he called up the Florida Museum of Natural History.
He had read a story about researchers at the museum who had used DNA from a tooth fragment to determine what kind of shark had attacked a 13-year-old boy off the coast of New York, and he was hoping they could do the same for him.
“We were quite surprised when Mr. Weakley came up to us,” Gavin Naylor, director of the museum’s shark research program, told As It Happens guest host Susan Bonner.
“We get a lot of inquiries from the general public and we always try to help them as best we can. But behind the scenes we thought, well, there’s absolutely no way this is going to work.”
‘Let’s just give it a college try’
Weakley, the editor of Florida Sportsman, had been surfing at Florida’s Flagler Beach in 1994 when something bit his foot, leaving him with stitches.
He always suspected it was a shark bite, but he never actually caught a glimpse of the creature responsible.
“I was very excited to determine the identity of the shark because I’d always been curious,” Weakley said in a museum press release.
“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.”
Weakley can now rest easy knowing it was, in fact, a shark. But figuring that out was no easy feat.
The tooth sliver was nested deep under Weakley’s skin for more than two decades, during which his immune system would have been working full time to produce enzymes that break down foreign objects.
Naylor figured any viable DNA would be long gone.
“My postdoc that actually did all the lab work, Dr. [Lei] Yang, he said, ‘Gavin, why are we doing this? It’s not going to work at all,'” Naylor said.
“I said, ‘I know, Lei, it probably won’t, but let’s just give it a college try.'”
First, they used a bleach mixture to rid the tooth of any “extraneous DNA.” Then they drilled into the part of the tooth that was still protected by enamel and obtained “an imperceptible amount of tissue” from which they extracted the DNA.
“Lei was the person that came back to me and said, ‘You’re not going to believe it, but I think this worked,'” Naylor said. “And I said, ‘Nah, it can’t possibly work.”
But it did.
Blacktip shark
When they cross-referenced the DNA with their shark database, they found a nearly perfect match — a blacktip shark, or Carcharhinus limbatus.
The species, which can reach 1.5 metres in length, often hunts for fish off Florida’s Atlantic coast. They’re generally timid and have no interest in preying on humans, but have been known to bite when frightened or provoked.
According to the museum’s species database, blacktips are responsible for roughly 20 per cent of the attacks that occur in Florida waters, though most result only in superficial wounds.
“I certainly don’t have a hatred of sharks or any feeling of vindictiveness toward them. They’re part of our natural world,” Weakley told the museum.
Though, he added: “I’ve consumed blacktip shark and thought it was delicious.”
Naylor, meanwhile, says he and his team would welcome any similar challenges in the future — so if you find a shark tooth in your body, you know who to call.
“It’s actually quite interesting to us to see the extent that we’re able to do this,” he said.
“So if other people do have, you know, things in their feet or in their arms, and it’s associated with a shark bite, then we’d be only too happy to help.”
Written by Sheena Goodyear. Interview with Gavin Naylor produced by Katie Geleff.
