Abstract
In this paper, we study the aggregation of a relatively high number of C. elegans roundworms resulting from the interaction between them and a set of external stimuli, namely oxygen and pheromones. Inspired by previous work, we delve into a hybrid modelling approach, simulating the aggregating behaviour of the worms by means of mathematical models, which we solve numerically, and by developing a phenomenological agent-based simulator. Our approaches capture the emergent aggregating behaviour of the worms, resulting in an interesting and coupled interplay between the macroscopic level, where probability distributions measure how the worms aggregate, and the microscopic level, where simple rules guide the agents to form clusters. Overall, our results suggest that there exists a strong correlation between the two approaches, indicating that they are able to capture the same phenomenon, albeit the mathematical model suffering from numerical limitations and the simulator requiring high computational resources. We then leverage our simulator in order to analyse the hypothetical behaviour of worms subject to both stimuli with different response levels, which results in a stronger degree of clustering than the single-stimulus simulation. We believe our framework can help shed light on the complex interactions between very large swarms of C. elegans, helping in predicting the emergent properties and reducing the amount of resources needed to run experiments with natural worms.