Fungi: Description and Identification

Fungi are opportunistic organisms that resemble both plants and animals but are actually neither. Fungi:

• Can exist as a single cell (like some yeasts) or as a multi-cell organism. 
• Are heterotrophic: like animals, fungi live off other organic material. Most plants are autotrophic, producing their own food via photosynthesis.
• Can reproduce by teleomorphic (sexual) or anamorphic (asexual) means, through fragmentation or by producing spores. The spores themselves can be sexual or asexual. 
  • Some fungi change from teleomorphs to anamorphs, adapting as environmental conditions around them change. 
  • Some fungi reproduce both sexually and asexually (“perfect fungi”). “Imperfect fungi” can only reproduce asexually.
• Digest their food externally, by excreting enzymes onto organic matter, then ingesting the matter back into their cells. Animals ingest food first, then digest it internally. 
• Can be saprophytic (feeding on dead or dying material).  Parasitic fungi obtain nutrition from a living host. Some, Armillaria mellea for example, transition from parasitic back to saprophytic, feeding on the organism it killed.

There are about 148 thousand identified species of fungi; a 2011 article suggests the total number is 5.1 million species. 

Related reading:

• THE FUNGI: 1, 2, 3 … 5.1 MILLION SPECIES? (American Journal of Botany*; 2011)

*= in LHL print collection