Condensed active matter systems regularly achieve cooperative emergent functions that individual constituents could not accomplish alone. The rafts of fire ants (Solenopsis invicta) are often studied in this context for their ability to create structures comprised entirely of their own bodies, including tether-like protrusions that facilitate exploration of flooded environments. While similar protrusions are observed in cytoskeletons and cellular aggregates, they are generally dependent on morphogens or external gradients leaving the isolated role of local interactions poorly understood. Here we demonstrate through an ant-inspired, agent-based numerical model how protrusions in ant rafts may emerge spontaneously due to local interactions and how phases of exploratory protrusion growth may be induced by increased ant activity. These results provide an example in which functional morphogenesis of condensed active matter may emerge purely from locally-driven collective motion and may provide a source of inspiration for the development of autonomous active matter and swarm robotics.

A ReadMe file is available with instructions for running the code, and subsequently post-processing the output data. The code provided represents the base-level code used in parameters sweeps for the final results presented. Various modifications were made to this code in order to implement aspects such as periodic boundary conditions, modulated surface agent activity level, etc. in investigation of specific things (e.g., unconfined self-propelled particle trajectory behavior, or activity's influence on global raft shape, respectively). Codes containing these specialty modifications are available in zip folders, also provided.

The agent-based model used to generate numerical results in this publication was written and processed in MathWorks® MATLAB R2019b. Additional raw data produced from the code and the post-processing methods used to generate specific results presented in figures are provided in zip folders with the designated names of said figures in their titles. Descriptions and instructions are generally provided in the "Run... .m" scripts provided in each folder.