Individually tracking whole weaver ant colonies to decode the behavioural rules of ant self-assembly

A project undertaken at the Department of Biological Sciences, Macquarie University and supervised by Chris Reid

Weaver ants (Oecophylla smaragdina) dominate their ecosystem by combining the best aspects of small individual size with coordinated collective power. They are one of only a few ant genera that can join their bodies together to create self-assemblages that perform vital functions for the colony. These structures include rope ladders that extend their reach, bridges that act as highways for ant traffic, and pulling chains to roll leaves together for nests. In the superorganism concept, where ants act as individual cells in a colony which represents a multicellular organism, the missing level of organisation is the tissue-level. Self-assembled structures fill this conceptual gap, creating the skeleton, circulatory system and muscles to exert force and create structure far beyond what individuals can achieve alone.

Ant self-assemblages are formed using simple agents and interaction rules, yet the emergent structures are sophisticated, forming when and where required, adapting to environmental conditions, and self-repairing when damaged.

This project will induce colonies to self-assemble pulling chains, bridges and hanging chains in the laboratory. Individuals will be uniquely marked and tracked using state-of-the-art technology to provide the first comprehensive quantification of behaviours during self-assembly, allowing me to statistically link individual-level behaviours to group-level functional outcomes. These data will be combined into a computer modelling framework that could benefit health areas (eg models of cellular self-assembly in embryonic development, wound healing etc) and engineering (swarm robotics control).

Figure 1. Ants crossing a gap by forming a small bridge under low traffic conditions. Image © Chris Reid

Figure 2. Ants forming a large bridge under high traffic conditions. Image © Chris Reid

Figure 3. Ants forming a hanging chain, forming a rope ladder down to the ground. Image © Chris Reid

Figure 4. Ants rolling an artificial leaf by forming pulling chains. Other workers will then bring silk-producing larvae to the rolled leaf, stitching it together to create a cavity for nesting in. (for short video click here) Image © Chris Reid