Fungal Launchers: The Biophysics of Spore Discharge and Dispersal

Pressure-powered spore-launching strategy is a unique feature for many fungal species. Fungal species have evolved this dispersal method to project spores into the surrounding environment, thereby increasing reproductive success and completing their life cycle. Sporangia squirters (like Pilobolus), ballistospore catapulters (like Agaricus), and ascospore launchers (like Neurospora) are prominent fungal cannons. Osmotic pressure and surface tension are responsible for propelling spores at extreme acceleration exceeding 20,000g and velocities reaching 94 km/h, thus enabling spores to travel distances of up to several meters. Thanks to advances in biophysical modeling and high-speed imaging, the century-old mystery of fungal launching strategies has been understood to involve principles of fluid mechanics, optics, and projectile dynamics, by investigating many fungal models. With a focus on the underlying biophysical principles and their broader implications for fungal ecology, this review summarizes current knowledge of morphology and biomechanics. Additionally, it discusses how each step of spore launching relates to fundamental physical principles of energy and motion.