The Domain Archaea is separated from the other two domains
by several distinguishing characteristics. The organisms that are in Domain
Archaea are prokaryotic, have ether-linked and branched membrane lipids, and live in extreme environments of which most
organisms cannot live in, for example: saline environments with 5.0 M NaCl; or
anaerobic environments. Domain Archaea is also discernible from Domain Bacteria
by its cell wall structure and ribosomal structure. Domain Archaea has two major
Kingdoms:
Euryarchaeota and
Crenarchaea (Holt, 2011). There also exist two minor kingdoms:
Korarchaeota and Nanoarchaeota.