Atta ants are more polymorphic than Acromyrmex, meaning comparatively less difference occurs in size from the smallest to largest types of Acromyrmex.

* Minims are the smallest and skinniest workers, and tend to the growing brood or care for the fungus gardens. Head width is less than 1 mm.
* Minors are slightly larger than minim workers, and are present in large numbers in and around foraging columns. These ants are the first line of defense and continuously patrol the surrounding terrain and vigorously attack any enemies