Scientists have discovered the fastest fliers in nature and, somewhat surprisingly, they're fungi!
Ohio-based researcher Nicholas Money and his colleagues at Miami University made the discovery by using ultra-fast cameras capable of taking 250,000 frames per second. Down the lens they were studying members of two fungal families - the ascomycetes and the zygomycetes - that do the essential but unsalubrious job of breaking down animal dung. These fungi rely on their spores passing harmlessly through the guts of grazing animals so that they land, quite literally, in the remains of their lunch. But animals generally avoid grazing in areas where another animal has defaecated, leaving fungi like these with a problem. Their solution is to have evolved the mycological equivalent of a "super-soaker" squirt gun - they fire their spores from tiny fluid-filled fruiting bodies so that they land in patches of uncontaminated grass ready for the next browsing ruminant. But although scientists realised that the fungal launchpad must be incredibly powerful, it was too fast and too small to surrender its secrets, at least until now.
Writing in this weeks PLoS ONE the team have successfully made fungal ballistic measurements of spore trajectories to reveal that these organisms are firing their microscopic projectiles, which measure just a fraction of a millimetre across, at speeds exceeding 25 metres per second and at rates corresponding to 180,000 times the acceleration due to gravity. This is sufficient to propel the spores up to 2.5 metres away from the parent dung pile.
The team were also able to get a handle on how the organisms achieve their fungal feat. A concentrated mixture of sugars, alcohols and other metabolites inside the fungus and its fruiting body pulls in water by osmosis, priming the gun at a pressure about four times that of the atmosphere. At the right moment the structure ruptures and the pressure drives out the spores. According to the researchers the images of these fungal ejaculations are so pretty that they've set them to music and plan to post them on YouTube!