Liquid lassos: The defensive spitting of a termite soldier

Nasutitermes (Termite) soldiers protect their mounds by spitting predators (ants) with a jet of viscoelastic fluid through the pointed nozzle of their cone-shaped heads. In this talk, we reveal the fluid dynamics underlying the high-speed ejection mechanism (max velocity ~ 0.4 m/s, spit time ~250 ms ) and the lasso-like dynamics of these natural viscoelastic jets in the air. We analyze the jetting instabilities of three different species of termites with different nozzle geometries observed in the Peruvian Amazon rainforest using field-portable high-speed cameras. Combining experiments and mathematical modeling, we demonstrate how the kinematics of the head motion and geometry of the nozzles (e.g. hyperbolic) influence the shape of the jets. We present a simple scaling argument governing the instabilities in the ejected filament. We envision that our understanding of this biological system will inform the optimal design of extrusion nozzles for 3D printing at the microscale.