The key to understanding fungi life histories is to bear in mind that the nuclei of a fungus are haploid, i.e. each nucleus contains a single set of chromosomes. The basically simple structure of the fungi resembled that of the simpler algae and for that reason the fungi were commonly defined as algal-like organisms without photosynthesis. Consequently fungal biology was often thought of as an offshoot of botany. Recent evidence suggests that the fungi are actually better placed near the animals than the plants. Basidiomycota and mushroom links in general.
Fungi are the dominant saprophytes of terrestrial ecosystems.
The hyphae secrete enzymes which desolve the dead organic material which is then absorbed by the hyphae. Not all fungi are saprophytes, however. Some fungi, apparently impatient for plants and animals to die, have become parasites. Atheletes Foot is one such parastic fungus. Many fungus are pathogens of plants.