In some ants, there are significant size differences within the worker caste. Depending on their size, the workers are minor, median or major. These are often disproportionate: head is larger and mandibles are stronger.

In some species, the average worker have disappeared, and their is a large physical gap between small and giant ants (sometime known as "soldier").

Contrary to what one might think, the defense is not their role. They are mainly used for grinding grain or cut solid foods.