Attraction, Dynamics, and Phase Transitions in Fire Ant Tower-Building

Abstract

Many insect species, and even some vertebrates, assemble their bodies to form multi-functional materials that combine sensing, computation, and actuation. The tower-building behavior of red imported re ants, Solenopsis invicta, presents a key example of this phenomenon of collective construction. While biological studies of collective construction focus on behavioral assays to measure the dynamics of formation and studies of swarm robotics focus on developing hardware that can assemble and interact, algorithms for designing such collective aggregations have been mostly overlooked. We address this gap by formulating an agent-based model for collective tower-building with a set of behavioral rules that incorporate local sensing of neighboring agents. We nd that an attractive force makes tower building possible. Next, we explore the trade-os between attraction and random motion to characterize the dynamics and phase transition of the tower building process. Lastly, we provide an optimization tool that may be used to design towers of specic shapes, mechanical loads, and dynamical properties such as mechanical stability and mobility of the center of mass. *

Treadmilling and dynamic protrusions in fire ant rafts

“…This activity endows unperturbed fire ants with the ability to dynamically change their raft shapes [ 19 ] and even form complex, three-dimensional (3D) structures such as towers nucleated about substrates [ 20 ]. While the behaviour and flow of 3D ant towers has been examined [ 20 , 21 ], questions remain regarding the long-term dynamics of approximately two-dimensional (2D) rafts. Mlot et al [ 11 ] reported that, upon being placed into the water as approximately 3D spheroids, ant rafts spread out rapidly.…”