Slime Moulds

These are a group of peculiar organisms which share characteristics of fungi and animals. Hence, they are also called as Mycetozoa. In the modern classification they are described as protistan fungi.

Most examples of slime moulds are terrestrial and occur in cool, moist and shady places in decaying logs, woods, decaying leaves and in soil rich in humus.

The vegetative parts do not have a cell wall. They occur either as free living multinucleate amoeboid mass of protoplasm called plasmodium or as an aggregation of amoeboid forms, called pseudoplasmodium. However, cell walls are seen in the reproductive stages. The name slime moulds comes from the fact that in the vegetative phase the organisms occur in the form of slimy masses.

The protoplasm found in the plasmodium of slime moulds is considered as the purest in the living world. It is differentiated into an outer enucleated hyaloplasm and a central nucleated portion. There are a large number of nuclei.

They are heterotrophic in nutrition since they lack photosynthetic pigments. Most of them are saprotrophic. Some are found as parasites on algae and other plants.

Slime moulds generally reproduce asexually by fragmentation or by forming sporangia, which produces spores having a cellulose cell wall. Sexual reproduction involves isogamy or anisogamy.

fig. 8.13 - Slime Moulds