Fungus

The fungi (Fungi) form the third major kingdom of eukaryotic organisms alongside the animals (Animalia) and the plants (Plantae). Like the plants, to which they have long been classed, they are sedentary, but cannot carry out photosynthesis. Therefore, like animals, they must feed by ingesting organic substances (heterotrophy), but they absorb them in dissolved form from the environment. According to current knowledge, fungi are more closely related to animals than to plants. They mainly include multicellular organisms such as the stander fungi, but also unicellular organisms such as baker's yeast as well as coenocytic forms with many cell nuclei but without cellular subdivision.

The science that deals with fungi is called mycology.

Etymology

The word mushroom (Old High German buliz) is borrowed from Latin bōlētus; the further origin is unclear. Probably the word is related to Ancient Greek βωλίτης bolites mushroom; Modern Greek βωλίτης vo̱líti̱s denotes thick boletus, especially the boletus (βωλίτης ο εδώδιμος), but also the Satan's boletus (βωλίτης ο σατανάς).

The botanical name Fungi (Latin fungus 'fungus') can be traced back to the ancient Greek σφόγγος sphóngos; this originally referred to sponges. Since fungi soak up water just like sponges, the term was transferred to mushrooms in the course of its history.

In the German language area the terms mushroom and sponge or Schwammerl exist parallel. In this context, species with a fleshy consistency were understood as mushrooms and those with a firmer wood-, leather- or cork-like tissue as sponges. At the same time, however, it was recognized that this division was not useful from a scientific point of view: some very similar species belonging to the same group would have been divided into the two categories; moreover, one and the same species would have belonged to the fungi when young and to the sponges when old, or vice versa. Sometimes the edible species were included under sponges, and the inedible species under fungi. But even this classification is untenable. The term Schwammerl still prevails in the southeastern part of the German-speaking world, while it has otherwise been superseded by Pilz.

Mycology, the word component mycetes and similar terms are derived from Ancient Greek μύκης mýkēs 'fungus' (plural μύκητες mýkētes).

Comparison with plants and animals

After fungi were assigned to the realm of plants from antiquity until the late 20th century due to their sedentary way of life, they are now considered to be a realm of their own and more closely related to animals than to plants on the basis of phylogenetic, biochemical and anatomical findings. Like animals, they belong to the relationship group (taxon) Opisthokonta. The separation of fungi from plants was first proposed by Robert Whittaker in 1969.

Fungi, like animals (which in biology also include humans), are heterotrophic (specifically chemoorganotrophic) and feed on organic nutrients in their environment, which they usually break down by releasing enzymes, thereby making them soluble and available for themselves. Another common feature of fungi and animals is that both form the polysaccharide glycogen as a storage substance, while plants form starch. The demarcation from the animal kingdom is not due to the immobility of fungi, since some animals, such as sponges or stony corals, also spend most of their lives stationary. Essential differences to the animals exist in the ultrastructure, so in the presence of cell walls and vacuoles (as in plants).

Fungi differ from plants primarily in the absence of plastids and thus chlorophyll-based photosynthesis. In addition, the cell wall of most fungi contains, among other polysaccharides, chitin, which does not occur in the plant kingdom, but is the main component of the exoskeleton of arthropods. Furthermore, fungi lack the polysaccharide cellulose, which is characteristic for plants.

A fundamental difference to other more highly organised organisms is that - apart from the formation of complex structures such as the fruiting bodies - each part of the organism is self-sufficient and there is no communication between the parts. Also an own daily rhythm, as animals and plants have it, seems to occur in fungi at best as an exception.