What Are They

Introduction
Members of this class are commonly referred to as slime moulds. These have thought to belong to both animal and fungi kingdoms at one time or another. It's now known that they are quite unrelated to animals and fungi and now are classified in the Kingdom Protista.

However slime moulds do exhibit characteristics of both fungi and animals. In the feeding stage, the slime moulds moves about as a mass of protoplasm (the plasmodium) feeding on bacteria, spores, and other organic matter much like an amoeba. When the food supply is exhausted or other unfavourable conditions occur, the plasmodium changes, taking on the appearance of a fungus.

Types
There are two main groups of slime moulds in the Protista Kingdom.

1 - Plasmodial slime moulds or true slime moulds are a large single-celled mass with thousands of nuclei called a plasmodium. They are formed when individual flagellated cells swarm together and fuse. The result is one large bag of cytoplasm with many diploid nuclei.

2 - Cellular slime moulds spend most of their lives as separate single-celled amoeboid protists, but upon the release of a chemical signal, the individual cells aggregate into a great swarm, known as a pseudoplasmodia and eventually muticellular slugs.

Habitat
The plasmodial stage is found in cool, shady, moist places on rotting logs, leaf litter, moist shaded soil, or other organic matter. There is around 1000 known species that feed on decaying organic matter, bacteria, protozoa, and other minute organisms, which it engulfs and digests. The plasmodium may reach several 100 millimetres in diameter and is often brightly coloured, although many are also inconspicuous.

Fruiting bodies

Life Cycle
Below is detailed a typical life cycle, but not all slime moulds will follow this exactly.

1 - Once a spore is released from the fruiting body it's dispersed, either by insects, animals, and rain or air movement. On landing on a suitable location with appropriate moisture and temperature, one to four protoplasts are germinated

2 - The protoplasts once released from the spore's wall through either a pore or fissure will be either a flagellated swarm cell if conditions are wet, or a non flagellated myxamoebae cell in dryer conditions.

3 - If conditions for growth are not suitable, the cells can become microcysts to survive long periods of time.

4 - A diploid zygote is formed when two compatible myxamoebae or swarm cells fuse. This is known as plasmogamy and karyogamy.

5 - After a time of feeding and growing, the zygote develops into a single celled multinucleate structure known as a plasmodium.

6 - If environmental conditions are not suitable, then the plasmodium can change into another dormant state known as the sclerotium.

7 - When the conditions are right, the mature plasmodium produces one to many fruiting bodies containing spores depending on species.