Ants organize their colonies through a system of division of labor based on caste systems. Each ant has a specific role within the colony such as foraging for food, caring for the young, defending the nest, or reproducing. The queen ant is responsible for laying eggs, while worker ants carry out various tasks to ensure the survival and success of the colony. Communication through pheromones also plays a crucial role in coordinating the activities of the ants within the colony.