SCIENCE ANTS SCHEME : SLIMMED DOWN

The secret to some ants' success is skin deep : There are around 20 quadrillion individual ants on Earth [ more than two million per human ], representing over 15,000 species, according to one estimate.

Their omnipresence bolsters their global importance as aerators of soil, recyclers of dead matter and dispersers of seeds.

A new paper investigated one way some of these tiny workers achieved such enormous success. 

For the study, published in the journal Science Advances, researchers measured the exoskeletons, or cuticles, of nearly a thousand ants across hundreds of species.

They found a correlation between thinner cuticles and larger colony sizes.

This suggests that over evolutionary time, some ant species may have made a '' trade-off between quality and quantity,'' raising their overall numbers by giving each worker slightly less cuticle, said Arthur Matte, a Ph.D student at the University of Cambridge a lead author of the new paper.

An ant's cuticle guards against threats at all scales, from fungal infections to looming hikers' boots. The thicker the cuticle, the better it protects. But cuticle-building requires nitrogen - a limited resource.

As a result, '' the costliness of producing a single worker is higher '' when that worker has larger cuticle, said Evan Economo, a professor at the University of Maryland and the Okinawa Institute of Science and Technology and one of the study's authors.

In 2017, researchers found that some ants' cuticles were just over a micrometer thick [ comparable to the length of a bacterium ], while those of others were nearly a hundred times as thick.

The World Students Society thanks Cara Giaimo.