Splash and grab: Biomechanics of peridiole ejection and function of the funicular cord in bird's nest fungi

• Published in: Fungal biology 2013-10, Vol.117 (10), p.708-714
• Main Authors: Hassett, Maribeth O., Fischer, Mark W.F., Sugawara, Zachary T., Stolze-Rybczynski, Jessica, Money, Nicholas P.
• Format: Article
• Language: English
• Subjects: Agaricales; Agaricales - cytology; Agaricales - physiology; Aves; basidiocarp; Basidiomycota; Biomechanical Phenomena; biomechanics; birds; browsing; Crucibulum; Cyathus; Dispersal; energy; Environmental Microbiology; flight; fungi; herbivores; High-speed video; Microscopy, Video; nests; Nidulariaceae; Spore discharge; spores; Spores, Fungal; vegetation
• ISSN: 1878-6146; 1878-6162
• DOI: 10.1016/j.funbio.2013.07.008

The bird's nest fungi (Basidiomycota, Agaricales) package millions of spores into peridioles that are splashed from their basidiomata by the impact of raindrops. In this study we report new information on the discharge mechanism in Crucibulum and Cyathus species revealed with high-speed video. Peridioles were ejected at speeds of 1–5 m per second utilizing less than 2 % of the kinetic energy in falling raindrops. Raindrops that hit the rim of the basidiome were most effective at ejecting peridioles. The mean angle of ejection varied from 67 to 73° and the peridioles travelled over an estimated maximum horizontal distance of 1 m. Each peridiole carried a cord or funiculus that remained in a condensed form during flight. The cord unravelled when its adhesive surface stuck to a surrounding obstacle and acted as a brake that quickly reduced the velocity of the projectile. In nature, this elaborate mechanism tethers peridioles to vegetation in a perfect location for browsing by herbivores. [Display omitted] •We used high-speed video to examine the mechanics of rain-splash discharge in bird's nest fungi.•Peridioles are splashed at speeds of up to 5 m s−1.•Peridiole discharge consumes 2 % or less of the kinetic energy in a raindrop.•Raindrops that hit the rim of the basidiome are most effective at ejecting peridioles.•An extensible cord functions as a brake that tethers peridioles to vegetation.