DNA From a Shark Tooth Embedded in a Man's Foot for 25 Years Identifies the Culprit

It was unclear what species of shark attacked Jeff Weakley while he was surfing off Flagler Beach, Florida in 1994. Whether it was a tiger shark, bull shark, great white shark, or some other predator didn't matter at the time—his priority was swimming to safety before the shark could take another bite.

Twenty-five years later, the wound on Weakley's right foot has healed, and he's had plenty of time to wonder what exactly bit him on that beach trip. By analyzing a tooth fragment that was lodged in his foot for more than two decades, a team of scientists has finally given him an answer, the Ocala StarBanner reports.

Bits of shark tooth have come loose from Weakley's foot several times since he was attacked in 1994. The third time it happened, in fall 2018, he collected the shard and sent it to the Florida Program for Shark Research, a part of the Florida Museum of Natural History in Gainesville. He had just read an article about the program's work identifying shark species using the DNA from their teeth, and he suspected the team might be able to do the same with his tooth fragment.

His hunch was correct: The scientists analyzed the sample and confirmed that the shark that had bit Weakley a quarter-century earlier had been a blacktip shark (Carcharhinus limbatus). That finding was made possible by years of hard work. Over more than two decades, the program has amassed a database of shark DNA containing reference samples for roughly 70 percent of all known shark, skate, ray, and chimera species. Luck was also on their side: The researchers had feared that Weakley's immune system would have destroyed any DNA in the shark's tooth, but when it arrived at the lab, there was enough to make the identification.

Shark attacks are common in movies and TV, but much less so in real life. You're more likely to be struck by lighting or die from the flu than be the victim of a shark attack. When sharks do bite humans, it's often because they've mistaken them for a prey animal, and they'll usually let the victim go once they've realized their error. This is likely how Weakley escaped his shark attack with his foot mostly intact.