ABSTRACT
Oceans cover 70% of the Earth’s surface with 97% of its water. Freshwater system, however, cover only 1% and hold 0.01% of its water. The remaining 29% of the Earth’s surface is covered by land. Surprisingly, of 106,761 fungal species, 1.0% (1,112 species), 2.7% (2,863 species) and 96.3% (102,786 species) are distributed in marine, freshwater and terrestrial habitats. A reason for their terrestrial abundance is traced to their spore dispersal cost. Spores are engaged by the majority of fungi for clonal and sexual reproduction. As water is 800-times denser than air, ~ 96% fungi have availed the cheapest aerial mode of spore dispersal on land. A second reason for > 96% fungal distribution limited to terrestrial habitats is the rapidity, at which the externally released digestive enzymes can be dissolved in water. Fungi grow and thrive, where water and carbon resources are available at temperatures between 10°C and 40°C. The extremes, at which they are recorded, are –6°C and +60°C and ~ 10,000 m depth in oceans. In deserts, where water availability in its liquid form is scarce, they draw moisture from fog. For example, ~ 302 fungal species are reported from mounts surrounded by fog in the Saudi Arabian Deserts.
