In herbivore dung lives an organism barely a few millimeters tall that holds one of nature's most impressive kinetic records: the fungus Pilobolus crystallinus, also known as the "hat-thrower." To ensure its survival, this fungus needs its spores to land far from the excrement where it was born, onto clean grass, so that another animal eats them and completes the digestive cycle.
To overcome the dense layer of stagnant air surrounding the surface, Pilobolus developed a biological cannon driven by osmotic pressure:
- Immense acceleration: The sporangium is launched with an initial acceleration exceeding 180,000 g, reaching a launch speed of up to 90 km/h in just two millionths of a second. In comparison, a bullet fired from a military rifle experiences about 40,000 g.
- The organic lens: At the tip of the stalk sits a swollen, transparent vesicle topped by a ring of carotenoid pigment. This structure functions like a true optical lens focusing sunlight, allowing the fungus to bend and aim with millimeter precision toward the brightest point of the morning sky.
- High-pressure rupture: When osmotic pressure inside the vesicle reaches about 5.5 bars (more than twice that of a car tire), the base ruptures and a jet of fluid propels the black capsule over two meters away and up to one and a half meters high.
Source: PLOS ONE (Yafetto et al., 'The Fastest Flights in Nature: High-Speed Webcam Analysis of Ascospore and Ballistospore Discharge in Fungi')
