The less derived (see apomorph) of the Archaea, consisting principally of extreme thermophiles and psychrophiles. Members of the Crenarchaeota show a greater genetic similarity to eukaryotes than to members of the Eubacteria. In the widely used five-kingdom system of classification, the Crenarchaeota form a group within the Archaea subkingdom of the Bacteria. In the three-domain system they comprise a kingdom within the domain Archaea.
Subjects: Ecology and Conservation — Plant Sciences and Forestry.