The fearsome reputation of the piranha may be a little over-exaggerated, but one thing that isn't a myth is the strength of that bite.
Scientists have found that the Black piranha (Serrasalmus rhombeus), along with an extinct species, Megapiranha paranensis, have the most powerful bite forces of any bony fish, living or extinct, relative to size.
The research, published in Scientific Reports, saw scientists test the biting power of 15 Black piranhas caught using barbless hooks in the Amazon River. The tests were done using gauge placed between their teeth and were described by the team as "rare, dangerous and difficult to perform".
They found the bite force of the Black piranha to be the strongest yet recorded for any bony or cartilaginous fish to date - more than 30 times its own weight and nearly three times greater than the bite force of an equivalent size American alligator.
The powerful bite is due to the extraordinarily size of the piranha's jaw muscles (which make up around 2% of the total body mass of S. rhombeus), along with a highly modified jaw-closing lever.
The team says: "When one considers their unique jaw functional morphology combined with their aggressive biting behaviour, it should come as no surprise that Black piranha whether large or small can rapidly and efficiently excise large chunks out of their prey."
Using data provided by Serrasalmus rhombeus, the team were also able to estimate the bite force of the extinct Megapiranha paranensis as up to 50 times its weight.
The researchers say that "a 73â€…kg Megapiranha's biting attack would have had the same ferocity of a 3000â€…kg Great white shark" and that "for its relatively diminutive size, Megapiranha paranensis' bite dwarfs other extinct mega-predators, including the enormous whale eating Carcharodon megalodon and the monstrous Devonian placoderm, Dunkleosteus terrelli."
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