Florida resident Jeff Weakley was bitten by a shark near Florida’s Flagler Beach back in 1994 and had long since put the incident behind him until he suddenly noticed that he had developed a lump similar to a blister on the same foot. He decided to pop the blister with some tweezers only to have a piece of shark tooth fall out.
According to scientists at the Florida Museum of Natural History, Mr Weakley had contacted them after the incident so they could run tests on the tooth to establish the species of shark it had once belonged to.
The Museum is currently running the Florida Program for Shark Research so it seemed was certainly the go-to lab for Mr Weakley. He was, however, concerned that when they ran the tests it might come back as something like a mackerel tooth, which would be a lot less exciting.
Testing the Tooth for Shark DNA
Scientist Lei Yang took the tooth and removed the pulp to test for DNA. It revealed that the tooth did indeed belong to a shark, specifically a Blacktip sharp. Known scientifically as Carcharhinus limbatus, this is a medium-sized shark that is often found in waters similar to that around Flagler Beach.
The event was reported in Wilderness & Environmental Medicine where laboratory manager Lei Yang explained how the test had been performed using modern genome sequencing to obtain an unambiguous result.
The University of Florida’s Naylor Lab has a DNA library of around 70% of all known sharks and similar species in the world and the Blacktip is one of the most abundant found in the Gulf of Mexico. Since they are so plentiful it is not uncommon for the Blacktip to be implicated in shark bite cases around Florida.
Mr Yang had some sympathy with Mr Weakley’s need to find out which shark had been the one to bite him. For his own part Mr Weakley said that this was confirmation of his initial belief that the shark had been a Blackfin.
That being the case, he still spent time in the ocean and the bite had never put him off swimming in the area. He likened it to being bitten by a dog, he was unlucky, but it was just a fact of life that sharks are present in the local area.
The team of scientists were lucky to be able to use the DNA in the tooth because it had been inside Mr Weakley’s body for around a quarter of a century, during which time it had undoubtedly come under fire from his own immune system.
Mr Yang was keen to point out that determining a species in the case of bites could be instrumental in understanding behavior and then implementing strategies that could help prevent future incidents. Each species is different in their life span, history and behavior so understanding the sharks is key to preventing more bites.