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n. pl. ar·chae·a (-kē-ə)
Any of various prokaryotic microorganisms of the domain Archaea, being genetically distinct from bacteria and often living in habitats with extreme environmental conditions such as high temperature or salinity. Also called archaebacterium.

[New Latin Archaeon (back-formed singular of Archaea, domain name), from Greek arkhaion, neuter singular of arkhaios, ancient (in reference to the very ancient separation of the archaea and the eubacteria in evolutionary history); see archaic.]


an order of prokaryotic microorganisms
References in periodicals archive ?
We tried to reproduce the putative Enceladus-like conditions in the lab," said Simon Rittmann, who studies microbes called archaea at the University of Vienna in Austria.
However, recently it was found that ammonia-oxidising archaea (AOA) may also play an important role in ammonia oxidation (Lcininger et al.
The study looked at protein structures in viruses and across all superkingdoms, or domains, of life: from the single-celled microbes known as bacteria and archaea, to eukaryotes, a group that includes animals, plants, fungi and all other living things.
By sampling fluids taken from the two wells over 328 days, the researchers reconstructed the genomes of bacteria and archaea living in the shale.
A study by the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the Medical University of Graz has found that the skin microbiome also contains Archaea, a type of extreme-loving microbe, and that the amount of it varies with age.
Valentine and Blair Paul, also of UCSB, along with scientists from UC Berkeley, UC San Diego and UCLA, showed that DGRs are active in the lineages of certain recently discovered archaea -- primitive, single-celled, bacteria-like microorganisms.
Long stretches of short tandem repeats are present in the largest replicons of the Archaea Haloferax mediterranei and Haloferax volcanii and could be involved in replicon partitioning.
Each of us is inhabited by unique populations of tiny organisms--bacteria, viruses, fungi, archaea, protists and mites--that consider our bodies home.
LUCA, the researchers say, was the common point of origin for three great domains of life - bacteria, archaea, which are bacteria-like single-cell prokaryotes, and the eukaryotes, a domain that includes all plants and animals.
When hydrothermal fluids mix again with seawater, together they provide a banquet of energy- and nutrient-supplying chemical compounds for microbes such as bacteria and archaea.
Microbial species are all forms of life too small to be seen with the naked eye, including all single-celled organisms, such as bacteria and archaea, as well as certain fungi.
So, archaea dwelling near superheated volcanic vents would definitely have a selective advantage for surviving a catastrophe like this," wrote commenter bruzote.