Which fungus carries a shotgun?
Pilobolus! To disperse its spores Pilobolus uses a "shotgun" to blast them as far away as possible. Pilobolus lives in dung, which may not sound like an appealing lifestyle, but without decomposers like Pilobolus we would soon be knee deep in it! In order to grow in dung, fungal spores must be eaten by an herbivore while it is grazing. The tough spores of Pilobolus pass through its digestive system unharmed and begin to grow as soon as they are excreted. Because herbivores (with the exception of rabbits) don't eat their own dung, Pilobolus has evolved a way to shoot its spores up to 2 metres. The "shotgun" is a stalk (sporangiophore) bearing a swollen tip, which contains a mass of spores (sporangia). At the base of the swollen tip is a light sensitive structure, which orients the growth of the stalk towards the Sun. Water pressure in the stalk and swollen tip builds up to more than 7 kg/cm2 (100 lb/square inch) before the tip explodes and the sticky spores are hurled out onto the grass where they will be eaten once again. Other coprophilous fungi found in the Arctic, such as Ascobolus and Podospora, have similar mechanisms to distribute their spores.