October 21, 2012
Bull Sharks, Not Great Whites, Have The Most Powerful Bite
redOrbit Staff & Wire Reports — Your Universe Online
The shark with the most powerful bite isn't the Great White or the Hammerhead, scientists have discovered -- rather, it is the Bull shark that bites with the most force relative to its size, according to a new study.
Marine biologists, including Philip Motta and Maria Habegger of the University of South Florida (USF), measured the bite strength from 13 different shark species, according to Dan Vergano of USA Today.
They discovered that a nine-foot-long Bull shark (Carcharhinus leucas) had a bite force of 478 pounds, while a Great White of similar size had a bite force of only 360 pounds.
"An 18-foot-long great white will still have a more powerful bite than an 11-foot bull shark, just by virtue of its size. But pound-for-pound, a bull shark of the same size would have a stronger bite," Motta told Vergano on Friday. "It's all about the width of the jaws, and bull sharks have very wide heads. We've seen sea turtles bitten in half, and that takes quite a lot of force."
"We expect strong bite force values in the larger sharks that occupy top positions in the food chain, for example, the great hammerhead, great white shark, tigers and bull sharks," Habegger added in an interview with BBC Nature Editor Matt Walker. "[But] sometimes size is misleading. Although larger size sharks will exert higher values of bite force, the relative value of bite force is what matters, pound per pound, how strong is the bite?"
Habegger, Motta, and colleagues from the U.S. and Germany tested a variety of sharks and shark-like creatures, including the one-meter-long ratfish and the Great White, Walker explained.
They dissected specimens of the 13 creatures studied to analyze their jaws and jaw muscles, then calculated the amount of force that those muscles put forth when the jaws of each creature closed. The effect that the size of each shark's body had on bite strength was then mathematically removed from the equation, in order to ensure a level playing field for the smaller specimens, he added.
So why do Bull sharks possess such ferocious jaw strength? The researchers admit they aren't sure.
"From our knowledge there is no need of such massive values to break fish skin or even to puncture bone," Habegger, a doctoral student at USF, said.
"One idea is that this ability gives young bull sharks an advantage over other competing species; allowing them to eat more diverse prey earlier in their lives," Walker added. "But overall, bull sharks, which the research shows can bite with a force of almost 6,000N at the back of the jaw and more than 2,000N at the front, seem to have bites that are too powerful."
Their findings have been published in the journal Zoology.