Forces and Motion

Forceful creatures

Stories from Physics for 11-14 14-16 IOP RESOURCES

Scientists have investigated the forces animals can exert. For example, paleobiologist Gregory Erickson and his team measured the bite force of all 23 species of crocodiles using force transducers. They noted that the maximum bite force exerted by all species exceeded the sheer force of bones. The highest force measured, 16,414 N, was exerted by a salt-water crocodile, much higher than the largest bite force recorded in a mammal, 4,500 N by a spotted hyena. Researchers studying black piranhas have measured the maximum bite strength of the fish to be 320 N for a 1.1 kg individual. The scientists report that a piranha’s bite force is around thirty times larger than its bodyweight, a ratio unparalleled amongst vertebrates. Extinct creatures had even stronger bites: a mega-piranha with a body mass of 73 kg is estimated to have had a biting force as high as 9,500 N. Bone analysis has allowed researchers to estimate the bite force of Tyrannosaurus rex as between 183,000 and 235,000 N for a bilateral bite. At the opposite end of the scale, a study has revealed that a Venus flytrap exerts a force of 450 mN and a maximum pressure of 9 kPa. Lemurs have been shown to have impressive arm strength – on average mouse lemurs were found to be able to pull over ten times their own bodyweight.




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