What are the benefits of a one-celled lifestyle?

The advantages of unicellular animals include microscopic size and easy adaptation to environmental conditions, so these organisms are able to survive in extreme conditions. Associated with this are parasitic existence, the experience of unfavorable conditions in a dry state in a cyst state, the ability to regenerate. The simplest far from primitive creatures, although they have one cell and organelles, which play the role of organ systems in multicellular forms, they exist as a full-fledged organism.