Revision:Fungi

  • There are over 80,000 identified species and the total number of species including unidentified species is likely to be in the region of 1.5 million giving Fungi a greater diversity than plants.
  • Fungi are closer related to animals than plants
  • Fungi vary greatly in size yeasts are unicellular fungi 4 – 12 µm long, some fungi have been found to have a kilometre of underground “roots.”

Feeding

Fungi are Heterotrophic meaning they are unable to produce their own organic carbon and must obtain it elsewhere. They do this by three different methods:

  • SAPROTROPHY – They obtain organic carbon from dead tissue
  • BIOTROPHY – They obtain organic carbon from living tissue either parasitically or in a symbiotic relationship.
  • NECROTROPHY – They obtain organic carbon from a source killed by the fungus.

Structures

  • HYPHAE – Tubular structures which form the mycelium. They are approximately 15µM in diameter. They grow at the tips which are extensible, behind the tip the hyphae become rigid. This method of growth is known as APICAL GROWTH. The hyphae may branch as new tips form behind the original tip. Hyphae are divided internally by partitions known as SEPTA. Septa tend to be incomplete and so do not divide the hyphae into discrete units. There are two components to the cell wall of hyphae, a fibrous component (usually CHITIN) and an amorphous paste (commonly constructed of polymers of Glucose (Glucans))
  • CABLES – Parallel arrays of hyphae, linear structures with a communicative role. RHIZOMORPHS have this structure.
  • ENCLOSURES – Play an important role in survival and reproduction, they have a variety of structures and functions. Examples include SCLEROTIA, PSEUDOSCLEROTIA, STROMATA and REPRODUCTIVE FRUIT BODIES. The last are the bit of the fungus you are likely to see; a mushroom is the reproductive fruit body of a fungus.

Reproduction

Fungi reproduce both sexually and asexually by diverse range of methods. When sexual reproduction is used both fungi can usually produce both the male and female organs.