Researchers at Georgia Tech have discovered that cicadas, unlike other xylem sap feeders, urinate in powerful jets rather than droplets. This observation, made during fieldwork in Peru, challenges established norms about insect urination and energy use.
Saad Bhamla, an assistant professor in the School of Chemical and Biochemical Engineering, and his research group hoped for an opportunity to study a cicada’s fluid excretion. However, while cicadas are easily heard, they hide in trees, making them hard to observe. As such, seeing a cicada pee is an event. Bhamla’s team had only watched the process on YouTube.
Second, smaller animals are expected to pee in droplets because their orifice is too tiny to emit anything thicker. Because of cicadas’ larger size — with wingspans that can rival a small hummingbird’s — they use less energy to expel pee in jets. Cicadas are the smallest animal to create high-speed jets, so they can potentially inform applications in making jets in tiny robots/nozzles. And because their population reaches trillions, the ecosystem impact of their fluid ejection is substantial but unknown. Beyond bio-inspired engineering, Bhamla believes the critters could also inform bio-monitoring applications.