Nowadays, it is essential to promote an interdisciplinary approach in classrooms, integrating disciplines such as biology and mathematics. This necessitates familiarity with specific problem-solving practices employed by the expert community, such as mathematical modelling. This perspective piece explores a mathematical modelling practice to analyse the effects of species mass on stable coexistence, demographic stability, and cascading intensity within a three-level food chain. Hypotheses are established regarding the use and significance of mathematics underlying the phenomenon in a biological context, taking into account both the pragmatic approach to mathematical knowledge and the ontological dimension of system conception. Modelling acts as an integrative bridge between disciplines, fostering effective collaboration between scientists and mathematicians in addressing complex problems, transcending the limits of specialisation, and acknowledging the essential characteristics of each discipline. The description of this modelling practice can support teachers in designing modelling tasks, thereby facilitating the integration of mathematical modelling with scenarios from the field of biology in the educational process.