A Florida man who discovered a tooth lodged in his foot from an attack that occurred a quarter-of-a-century ago now knows a shark bit him, thanks to DNA testing.
In 1994, Jeff Weakley was surfing off Flagler Beach in Florida during a college beach mixer when something briefly chomped on his foot.
The 21-year-old experienced surfer shook off the creature, but never caught a glimpse of what grabbed him. He suffered lacerations to his toes and joint damage, recently published in the journal Wilderness & Environmental Medicine.
In the summer of 2018, Weakley discovered a tooth that had been embedded in his foot after he used tweezers to open up a recently formed 鈥渂lister-like bulge.鈥�
Although he initially considered turning the tooth into a pendant, Weakley changed his mind and donated it to Florida Museum of Natural History after hearing about how researchers there analyzed the DNA of a shark tooth from another attack off of New York to determine the responsible species.
鈥淚 was very excited to determine the identity of the shark because I鈥檇 always been curious,鈥� for the study Tuesday. 鈥淚 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鈥檇 been bitten by a mackerel or a houndfish 鈥� something really humiliating.鈥�
Weakley鈥檚 fears were alleviated when the testing revealed he had, indeed, been bitten by a shark and one particularly prone to attacks at that.
It was a blacktip shark, or Carcharhinus limbatus, that left a tooth behind during its taste of Weakley鈥檚 foot, according to the researchers. The shark species doesn鈥檛 hunt humans, but it鈥檚 known to accidentally bite people in cases of mistaken identity, particularly along the Florida coastline.
While Weakley said he wasn鈥檛 surprised a blacktip shark was behind the attack, researchers at the museum were amazed they were able to retrieve that genetic information from the tooth given the number of years it was embedded inside the man鈥檚 foot.
鈥淚 had put our odds of success at slim to none,鈥� Gavin Naylor, the director of the museum鈥檚 Florida Program for Shark Research, said.
The scientists said that鈥檚 because the tooth would have been subjected to mammalian physiological temperatures, enzymes, and an immune system designed to break down and target foreign tissue.
鈥淒espite some DNA degradation, the sequences we obtained in this case were still sufficient to assign the tooth fragment to a species,鈥� the study said.
In order to test the DNA, the program鈥檚 laboratory manager Lei Yang cleaned the tooth of contaminants, removed part of the enamel, and scraped pulp tissue from the cavity before extracting DNA from it. He then purified the DNA and compared its sequences to those in two databases consisting of shark and ray genetic information.
鈥淚f I was bitten by a shark, I would want to know what it was,鈥� Yang explained.
Determining the species of sharks responsible for attacks on humans can provide researchers with a better understanding of the circumstances surrounding shark bites and how to prevent them, the study said.
鈥淎bout 70 per cent of shark bites are caused by unidentified species, and more precise data on which species are involved could improve bite mitigation strategies,鈥� Yang said.
As for Weakley, he said he has no ill will towards the shark that bit him all those years ago.
鈥淚 certainly don鈥檛 have a hatred of sharks or any feeling of vindictiveness toward them. They鈥檙e part of our natural world,鈥� he said.
In fact, the avid surfer was back out in the water within weeks of the bite and he continues to surf and fish regularly.
The museum鈥檚 findings are .
