The biomechanics of viscous spitting in termite soldiers

Soldiers of the tropical Nasutitermites species protect their colonies from intruders by expelling an adhesive fluid jet through their nozzle-like heads. While previous studies have provided a qualitative account of this unique behavior, the precise mechanics of how these fluid jets contribute to the termites' 'fortress defense' strategy remains a mystery. In this presentation, we delve into the fluid dynamics and physical characteristics of these tiny jets (V~10 nL, D~ 10 m), captured through high-speed imaging and micro-rheological experiments in the Peruvian Amazon rainforest. Through mathematical and experimental evidence, we demonstrate how these termites harness head oscillations to transition from creating liquid rope coils to forming substantial lasso-like viscous threads that can reach twice their body length. This unusual technique helps them fend off more sizable predators. Using micro-CT scans and computational fluid dynamic simulations, we create a model of the pressure-driven flow through their pointed heads (or nasus) and explore the impact of its geometry on the jet dynamics. By understanding the biomechanics of these termites and the fluid mechanics of the microjets they emit, we can not only expand our knowledge of the biophysical boundaries of their defensive behavior, but also potentially inform the design of microscale jet extrusion nozzles.