The big, big world is run by people who play different roles according to social classes. In the smaller ant world, social classes may well exist too.

As in popular belief, ants are hard-working. While we wonder about those little armies of colonies toiling every day for food, some other groups of ants are at home sitting pretty, or just hanging around.

Scientists looked at the behavior of ants and found a number of lazy ants doing nothing.

For three days, researchers from the University of Arizona observed 250 marked ants of the Temnothorax rugatulus found in the forests of western North America, and noted a consistency in their immobility and published their findings the journal Behavioral Ecology and Sociobiology.

The ants were classified into three according to their performance and activity: active, inactive and undifferentiated. Active ants are the working ants, normally foraging, carrying brood or building. Inactive ants are those not doing anything, completely immobile. Undifferentiated ants would be ants that could be walking around, but not really "working."

Almost half of the time, ants were found to be inactive.

The lazy ants of the Temnothorax rugatulus species are bigger in size than the workers. They tend to keep to themselves and interact less, according to Daniel Charbonneau, lead researcher.

Scientists are certain that there are a number of lazy ants too, but as to how and why, they cannot fully tell yet.

Some speculations and hypotheses come to mind as to why these ants are lazy.

The lazy ants could be acting like those of the honey pot ant species, where ants are 'appointed' as live feed stations to the exhausted working ants. The appointed honey pot ants hang still from the roof of their nest and supply "drinks" that have been stored in their abdomens. The lazy Temnothorax rugatulus can possibly serve the same purpose.

Another hypothesis springs from the theory of Tomer Czaczkes from the University of Regensburg in Germany. The colony of inactive ants could only be standing by as an "army reserve" to assist in challenging tasks, fight attackers or replace workers when they die.

Charbonneau said that high levels of inactivity are found not only in ants but other insects as well. Fitness costs and benefits of ant inactivity and mechanisms in inactivity that might affect colony fitness are just some of the things Charbonneau is aiming to figure out, in his continued study of ants.