This volume covers the fields of origin, evolution and phylogenesis from prokaryotic to eukaryotic cells. The eminent authors, experts in their fields, review the three kingdoms of life (Archea, Eubacteria and Eukarya) from molecular evolutionary levels to ecological aspects in enigmatic habitats, including general reviews of puzzling pro — and eukaryotic organisms and their domains. We discuss dry habitats, thermophilic (cells in hot springs and undersea thermal vents up to 110`C), psychrophilic (cryophiles) and halophilic (high salt concentrations) niches which among the harshest conditions found on Earth where microbial life is frequently detected. Some chapters deal with the organisms which grow in extreme pH conditions (acidity vs. alkalinity), and under hydrostatic pressure in the deep sea, and microbial growth on petroleum. Other contributors present their research on aerobiology and microbes growing in various gases and various levels of radiation, including cellular morphological modification in these extremophilic microbes. This volume also includes the symbiotic association between two or more organisms on the endocellular and exocellular levels. Finally one paper identifies the extremophiles as candidates for exobiology. This is a valuable comprehensive volume in English that covers most of the extremophiles in a new light with current research data. Audience: Students, lecturers and researchers; scholars in the fields of biology, evolutionary biology and chemistry, and other evolutionary fields, and the intelligent layman.