The worker ant is a sterile female whose existence is dedicated to the survival and prosperity of her colony. Operating as part of a “superorganism,” workers perform specific tasks through a sophisticated division of labor to ensure the colony’s efficiency and growth.
Internal Colony Maintenance and Brood Care
A significant portion of the worker population is dedicated to tasks performed exclusively within the nest chambers and tunnels. These internal workers, often the younger members, are responsible for the colony’s infrastructure and the welfare of the developing young. They maintain the nest by excavating new tunnels, expanding chambers, and making structural repairs.
Brood care is a specialized duty involving tending to the eggs, larvae, and pupae. Workers move the vulnerable brood between chambers to maintain optimal temperature and humidity levels for proper development. Immobile larvae are entirely dependent on workers for nourishment.
Feeding the young and sharing food among adults is managed through trophallaxis, where an ant regurgitates liquid food from its crop to another ant or directly to a larva. This mouth-to-mouth exchange facilitates the transfer of chemical signals, hormones, and immune-boosting compounds throughout the colony, creating a “communal stomach.” Workers also ensure nest sanitation by removing waste, debris, and the bodies of dead nestmates, minimizing the risk of disease.
Resource Acquisition and Colony Defense
As workers age, their duties transition to the external world, focusing on resource acquisition and territory protection. Foraging involves scouting, locating, and transporting food items such as seeds, nectar, or insect prey back to the nest.
Ants use chemical communication extensively to coordinate these activities, employing pheromones to mark trails to newly discovered food sources. This chemical trail allows other foragers to be rapidly recruited, maximizing the speed and quantity of resource collection. In some species, different worker sizes, or sub-castes, are specialized for foraging, with larger workers sometimes traveling farther from the nest.
Defense of the colony is another external function, involving guarding the nest entrance and patrolling foraging trails. Workers engage in confrontations with predators and rival ant colonies to protect the nest and its resources. In species with specialized soldier ants, these individuals are often larger and more robust, equipped with powerful mandibles that make them more effective against external threats.
The Progression of Worker Roles
The shift in a worker ant’s job over its lifetime is known as age polyethism. Newly emerged workers, often pale, begin their lives performing the safest tasks deep within the nest, such as nursing the brood and cleaning. This initial phase allows them to gain experience and for their exoskeletons to fully harden. As the ant matures, it gradually moves outward, transitioning to tasks like nest construction. The final, and riskiest, stage involves foraging and colony defense outside the nest.
This age-based specialization maximizes the worker’s lifetime contribution; if an older ant dies while foraging, the colony loses a less valuable individual than a younger worker. For some tasks, physical capability also drives this progression, as seen in leaf-cutter ants. Younger workers, called callows, may lack the muscle force and rigidity required for the demanding task of cutting leaves.