Fishy forensics – telltale teeth
Turning a forensic eye on tooth mark evidence left by a shark when it bites may tell us what kind of shark sunk its teeth in. A new forensic technique that looks closely at dried shark jaws has created a directory of the bite patterns left by different species and sizes of shark.
Scientists from the University of Florida have measured the jaw circumference and the distance between the six frontal teeth on the top and bottom jaws of 14 different shark species. They studied between 10 and 24 sets of shark jaws from each species.
Knowing the type of shark that bites can give researchers valuable information. A bite in a turtle or dolphin can tell you about the diet and habits of certain shark species. For people who have been nibbled on by a roving shark, knowing which type of shark has bitten them is psychologically important.
This sort of fishy forensics could also save countries money. Sharks don’t just sink their teeth into sea animals, people and surfboards; they can also take a bite out of valuable communication cables that lie on the ocean floor.
Sharks are attracted to the electrical current running through underwater communication cables. Thinking that these cables might be a tasty treat, a shark can do thousands of dollars worth of damage with a bite. They are able to sense electromagnetic fields made by electrical currents and may have the highest electromagnetic sensitivity of all animals.
“That’s one thing that makes them special — they can sense electro-magnetic fields around their prey items,” said shark researcher George Burgess from the University of Florida.
An organ called the ampullae of Lorenzini lets sharks detect electromagnetism in water. This organ is a network of jelly-filled canals found in a shark’s nose and head. Each canal has a pore that opens to the water.
If we knew the type of sharks that were biting cables, the cable could be designed to withstand that particular species’ bite.
By Beth Askham