Ants are cultural signifiers of busy industriousness, but a new paper in Plos One reveals that, across species, about 40% of "worker" ants spend most of their days doing nothing.
The researchers hypothesize that the "lazy" ants form both a reservoir of genetic material and a reserve workforce that serves as a hedge against the death of the "productive" ants. They may also serve as an emergency food supply for hard, cannibalistic times.
Analyzing the video recordings revealed that a colony breaks down into four main demographics, according to Charbonneau: inactive, lazy ants; so-called walkers that spend most of their time just wandering around the nest; foragers that take care of outside tasks such as foraging and building protective walls from tiny rocks; and nurses in charge of rearing the brood.
Charbonneau observed that the lazy ants tend to have more distended abdomens, hinting at the possibility that they could serve as "living pantries." Published in another recent paper, this observation awaits further testing to determine whether their larger circumference is a cause or a consequence of the lazier workers' lifestyle.
To see what would happen if the colony lost sizable amounts of inactive members, Charbonneau and Dornhaus did a separate experiment in which they removed the least active 20 percent. They found that those ants, unlike their top-performing peers, were not replaced.
Who needs 'lazy' workers? Inactive workers act as a 'reserve' labor force replacing active workers, but inactive workers are not replaced when they are removed
[Daniel Charbonneau, Takao Sasaki and Anna Dornhaus/Plos One]
(via Beyond the Beyond)