Mycetozoa
The slime molds ( Eumycetozoa ) are a taxon of single-celled organisms that combine in their lifestyle characteristics of animals and fungi alike, but belong to neither of the two groups. Despite their name, so they are not mushrooms.
The group comprises just over 1000 species, but the number is considered to be inaccurate. After recent considers that the slime molds no longer represent the common group contained three taxa Myxogastria, also known as Myxomycetes (as largest group ), and Dictyostelia Protostelia are no longer together.
Within biology, the systematic study of slime molds is operated by the Botany and Mycology.
Characteristics and life cycle
Slime molds pass through several morphologically very different stages in their lives. Your particular appearance is inextricably linked with its life cycle.
Features
From the fruiting bodies spores arise from these, amoeboid organisms. The amoebae are varied, but always have tubular cristae and tapering pseudopods. Initially it is mononuclear Amoeboflagellaten or amoebae.
Maturity slime molds can in appropriate circumstances fruiting bodies form, either as an emerging from a single amoeboid cell Sporokarp at Myxogastria and Protostelia, or as Sorokarp in the subclass of Dictyostelia which comes together from aggregations amoeboid single cells.
The actual formation of the fruiting body can go one of two ways to go. Firstly, as with the types of Myxogastria and Protostelia in which individual plasmodia of negative change to positive phototaxis, to move towards the light and see a high place, which is the light and thus also exposed to the wind in order to ideal spores spread where them the fruiting bodies, the so-called Sporokarpe that form.
Considerably more complex the processes are the representatives of the subclass Dictyostelia. Here are collected the hitherto living as a single amoeba cells and form a so-called Pseudoplasmodium, a temporary multicellular organization, which moves like snails. At the right place arrived, it again undergoes a metamorphosis: a portion of the cells forms a stem and other so-called sorus that contains the spores. Here is the fruiting body, the so-called Sorokarp, not expression of a cell, but a cell network.
Habitats
The majority of all slime mold species live terrestrial, only a few species is a completely submerged life known. However, distinguishing can be various so-called microhabitats. The most important microhabitat is deadwood, moreover, of importance are the bark of living trees, rotting plant material of the scattering horizon, soils and animal excrement. A rare special form primarily tropical species is the colonization of living leaves of plants. Mostly, slime molds found in open woods, but as far as the basic conditions are present, you meet slime molds also in unusual places such as deserts (for the Sonoran Desert alone are 33 species detected ), the melt water of alpine snow drifts as well as in regions of particularly high latitudes.
Dissemination
Slime molds are common with the majority of their species worldwide, however, occur in temperate latitudes on much more frequently and with higher species richness than in the subtropics and tropics.
The reasons for the lower incidence in the tropics, the light poverty of the local forests ( impairment of positive phototaxis ), wind (adversely to distribute the spores), infestation by molds favoring humidity, very acidic soils, a variety of predators and frequent, extremely heavy rainfall that can wash off or destroy the cells, called.
Importance
For humans, slime molds are largely unimportant, a few species are used in biology as a model organism from two Myxogastria of use is reported as food. There are no known toxic agents.
System
The class of slime molds comprises around 1,000 to 1,100 species. In 2007, a work estimated the number of species to well over 1000, then the subclass Myxogastria as by far the largest group of slime molds comprised of well over 900 species, with over 100 species was already significantly smaller subclass Dictyostelia, the smallest subclass, however, the Protostelia, included only 36 species. Estimates based on sequenced environmental samples assume that the group is significantly greater than previously known ( Myxogastria: 1200 - 1500 species, Dictyostelia: ~ 300, Protostelia: 150).
The following system is essentially based on Adl et al. 2005, in the stands and the further subdivision of the largest group, the Myxogastria, but it takes on the scheme of Dykstra and Keller 2000. Whether genre Guttulinopsis is to provide a genus of slime molds or the Heterolobosea is unclear.
- Subclass Myxogastria order Liceida
- Order Echinosteliida
- Order Trichiida
- Order Stemonitida
- Order Physarida
- Subclass Protostelia order Protosteliales
- Subclass Dictyostelia genus Acytostelium
- Genus Coenonia
- Genus Polysphondylium
- Genus Dictyostelium
- Incertae sedis: Copromyxa
- Copromyxella
- Fonticula