According to a team of scientists headed by Prof Guillermo Ortí of the Columbian College of Arts and Sciences, the extinct megapiranha (Megapiranha paranensis) and the black piranha (Serrasalmus rhombeus) have the most powerful bites of carnivorous fishes, living or extinct.
Piranhas’ aggressive nature, relatively small size and accessible populations make them a suitable group of predatory vertebrates in which to study the evolution of extreme biting capabilities. Even at their small body sizes, diet studies indicate that piranhas will attack and bite chunks of bony fins and flesh from prey many times larger than themselves.
In spite of their reputation, no quantitative data or empirical estimates regarding the piranhas biting abilities were available.
Prof Orti and colleagues participated in a 2010 expedition to the Xingu and Iriri rivers in Amazonia to collect the data on the black piranha.
The study, published in the Scientific Reports, reveals the bite force of the megapiranha (identified in 2009), showing that for its relatively diminutive body size, the bite of this fossil species dwarfed that of other extinct mega-predators, including the whale-eating shark and the Devonian placoderm.
The study also reports the first bite-force measurements taken from wild specimens of the black piranha, and describes the underlying functional morphology of the jaws that allows this creature to bite with a force more than 30 times greater than its weight.
The powerful bite is achieved primarily due to the large muscle mass of the black piranha’s jaw and the efficient transmission of its large contractile forces through a highly modified jaw-closing lever.
“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,” said Dr. Orti. “I learned a lot of biomechanics from my colleagues while collecting valuable specimens for my own research.”
“An anterior bite force of 320 N from the black piranha is the strongest bite force recorded for any bony fish to date. Results indicate megapiranha’s bite force conservatively ranged from 1240–4749 N and reveal its novel dentition was capable of resisting high bite stresses and crushing vertebrate bone,” the scientists wrote.
Bibliographic information: Grubich JR et al. 2012. Mega-Bites: Extreme jaw forces of living and extinct piranhas (Serrasalmidae). Scientific Reports 2, article number: 1009; doi: 10.1038/srep01009