SUMMARY
Many organisms, from cells to ants to bees, can link their bodies together to build large aggregations. The robustness of these structures depends on their ability to adapt to changes in environmental conditions. In this thesis, we report experiments detailing how fire ant aggregations respond to changes in numbers of ants, temperature, and flow speed. We report metabolic rates of aggregations, statistics of random walks, and changes in aggregation shape based on fluid flow speed. Particular attention is paid to using numerical modeling to determine the individual rules that underly the observed collective behaviors. The goal is to determine new principles in responsive collective behavior, which may give inspiration to physics, biology, and robotics.