December 21, 2012
Black Piranha And Megapirahna Hold Record For Most Powerful Bite
Brett Smith for redOrbit.com — Your Universe Online
In an attempt to calculate the bite force of the extinct Megapiranha, an international team of marine biologists have said the modern-day black piranha, along with its extinct counterpart, have the most powerful bite of any apex predator, for its body size.
In the study, the team of scientists collected 15 black piranha specimens from Xingu and Iriri tributaries of the Amazon River in Brazil using nets and fishing techniques. To minimize their impact on the fish and maintain their integrity, the scientists used barbless hooks and conducted bite-pressure tests immediately after the fish were caught.
According to the report, the fish “readily performed multiple defensive bites with the transducer placed between the tips of the jaws.”
Some fish were dissected in the field to examine and record the morphology of their jaws.
These observations allowed the scientists to describe the underlying physiology of the jaws that gives this creature the ability to bite with a force of over 30 times greater than its body weight. The large, yet short, muscle mass in the black piranha´s jaw and highly specialized jaw-closing lever allows the fish to chomp down with remarkable force.
Based on the data collected from the black piranha, the researchers made conservative estimates about the bite force of the much larger, but extinct, Megapiranha. Without definitive fossil evidence, the team had to assume the extinct piranha and the black piranha, a close evolutionary relative, shared a similar jaw physiology.
They determined the extinct fish bit down with a force four times greater than the largest black piranha. They also found the Megapiranha would have been able to bite into a bovine femur with no problem. Turtles and armored catfish, two of the Megapiranhas contemporaries, would have stood little chance against the crushing bite.
Inspired by their calculations, the authors of the report wondered–what exactly were these fish eating that required such a strong biting force?
“Did Megapiranha use their strong jaws and novel dentition to not only slice into their prey's compliant flesh, but also crush through their stiff bones? Our bite simulations indicate Megapiranha's hybrid teeth were indeed capable of transmitting sufficient bite pressure to generate micro-fractures in robust cortical mammalian bone as well as complete mechanical failure of thinner vertebrate bony tissues,” the authors wrote in their report.
Based on the known tooth morphology of Megapiranhas, the scientists posited the big fish did indeed hunt turtles and bony fish.
The fieldwork portion of the study was organized and filmed by National Geographic. Some of the footage shot in the field was used in a program called Megapiranha, which aired on the National Geographic Channel.
“It was very exciting to participate in this project, travel one more time to the Amazon to be able to directly measure bite forces in the wild,” Guillermo OrtÃ, a George Washington University Professor of Biology, said in a statement. “I learned a lot of biomechanics from my colleagues while collecting valuable specimens for my own research.”