Acellular or plasmoidal slime moulds
General characters :
- Slimy masses found on decaying leaves and lumber.
- Somatic body is free living, multinucleate, naked, diploid mass called plasmodium. Movement occurs by means of pseudopodia.
- During unfavourable conditions, entire plasmodium forms many fructifications / fruting bodies (polycentric). The fruting body is called sporocarp which contains a stalk having a sporangium at its tip. The wall of sporangium is called peridium.
- Sporangium has an intricate network of cytoplasmic threads called capilitium.
- Diploid protoplast forms haploid spores by meiosis
- Spore wall is double, outer wall is spiny and sculptured.
- On germination, spores produce biflagellate swarm cells or non- motile myxamoebae which act as gametes.
- Sexual reproduction is isogamous.
- Diploid zygote directly forms the plasmodium which becomes multinucleate by repeated mitotic divisions of the diploid nucleus.
- Chief mode of nutrition is saprotrophic.
- Vegetative reproduction is by fission.
e.g., physarum. Physarella, Fuligo, Dictydium , Lycogala,
