MIAMI (AFP) - The mighty cockroach packs a powerful bite, thanks to jaws that can grind five times stronger than a human, or with 50 times more force than the bug's body weight, researchers said Wednesday.
The creatures don't always chomp so ferociously.
Only if they need to chew through tough materials like wood will they activate certain slow twitch muscle fibres in their jaw in order to launch a force boost that is necessary for a repetitive, heavy-duty task, said the study in the journal Plos One.
"Ours is the first study to measure the bite forces of ordinary insects, and we found that the American cockroach, Periplaneta americana, can generate a bite force around 50 times stronger than their own body weight," said lead author Tom Weihmann from the University of Cambridge's Department of Zoology.
"In relative terms that's about five times stronger than the force a human can generate with their jaws."
Researchers wanted to understand the cockroach's bite because insects play a crucial role in many ecosystems and findings could enable "bioinspired engineering," said Weihmann.
So the team analyzed 300 bites made by specimen cockroaches, ranging from quick and feeble bites to powerful, long-lasting ones.
"The weaker, shorter bites were generated by relatively fast muscle fibres, while the longer, stronger bites were driven by additional muscle fibres that take time to reach their maximum force," said Weihmann.
"These slower muscle fibres give the mandibles a force boost to allow them to exert up to 0.5 Newtons during sustained grasping or chewing."
Cockroach mouths contain a pair of horizontally aligned blade-like jaws, which they use for shredding food, digging, carrying things, defending themselves and feeding their young.
While these kinds of jaws are not particularly unique in the insect world, researchers were impressed by how the slow muscle fibres allowed "very efficiently generated muscle forces with only a minimum of cross-section area, and therefore head volume, required," said Weihmann.
Perhaps someday, engineers will be inspired by cockroaches to design tiny motors or micro-probes that can deploy great force despite their small size.