Note: Wilson (1980b) studied Atta sexdens but caste system similar across Atta species (e.g., Hölldobler and Wilson 1990; Hölldobler and Wilson 2011).
In the Atta labor system, striking differences in body size and anatomy exist between the smallest and largest workers.
Forager with hitchhiker on top of leaf fragment.
Atta leafcutter ant colonies are comparable in social complexity with honeybees.
Small, young workers tend and harvest fungi in subterranean chambers, but some also "hitchhike” on leaves to begin the leaf-cleaning process and defend leaf-carrying ants against parasitic flies.
Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.