Talk:Archaea

Lead section

The lead section currently begins,

Archaea (/ɑːrˈkiːə/ ⓘ ar-KEE-ə) is a domain of organisms. Traditionally, Archaea only included its prokaryotic members, but this since has been found to be paraphyletic, as eukaryotes are now known to have evolved from archaea. Even though the domain Archaea cladistically includes eukaryotes, the term "archaea" (sg.: archaeon /ɑːrˈkiːɒn/ ar-KEE-on, from the Greek "ἀρχαῖον", which means ancient) in English still generally refers specifically to prokaryotic members of Archaea. Archaea were initially classified as bacteria, receiving the name archaebacteria (/ˌɑːrkibækˈtɪəriə/, in the Archaebacteria kingdom), but this term has fallen out of use.

Archaeal cells have unique properties separating them from Bacteria and Eukaryota. Archaea are further divided into multiple recognized phyla. Classification is difficult because most have not been isolated in a laboratory and have been detected only by their gene sequences in environmental samples. It is unknown if they are able to produce endospores.

Archaea and bacteria are generally similar in size and shape, although a few archaea have very different shapes, such as the flat, square cells of Haloquadratum walsbyi. Despite this morphological similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes ...

The first paragraph has 4 sentences. To me it seems like the second and fourth sentences should be moved to later in this section. If we did that, the lead section would read

Archaea (/ɑːrˈkiːə/ ⓘ ar-KEE-ə) is a domain of organisms. Even though the domain Archaea cladistically includes eukaryotes, the term "archaea" (sg.: archaeon /ɑːrˈkiːɒn/ ar-KEE-on, from the Greek "ἀρχαῖον", which means ancient) in English still generally refers specifically to prokaryotic members of Archaea.

Archaeal cells have unique properties separating them from Bacteria and Eukaryota. Archaea are further divided into multiple recognized phyla. Classification is difficult because most have not been isolated in a laboratory and have been detected only by their gene sequences in environmental samples. It is unknown if they are able to produce endospores.

Archaea and bacteria are generally similar in size and shape, although a few archaea have very different shapes, such as the flat, square cells of Haloquadratum walsbyi. Despite this morphological similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes ...

I am interested in hearing other editors' thoughts. T g7 (talk) 15:20, 28 January 2025 (UTC)

Some rearrangement may be sensible, but the proposed paragraphs feel very short and choppy. Chiswick Chap (talk) 15:27, 28 January 2025 (UTC)

How about this:

Archaea (/ɑːrˈkiːə/ ⓘ ar-KEE-ə) is a domain of organisms divided into multiple recognized phyla. This domain cladistically includes eukaryotes, but the term "archaea" (sg.: archaeon /ɑːrˈkiːɒn/ ar-KEE-on, from the Greek "ἀρχαῖον", which means ancient) in English generally refers to unicellular, prokaryotic members of Archaea. Archaeal cells have unique properties separating them from Bacteria and Eukaryota, although eukaryotes evolved from archaea.

Archaea and bacteria are generally similar in size and shape.[6] Despite this morphological similarity to bacteria, archaea possess genes and metabolic pathways that are more closely related to those of eukaryotes, notably for the enzymes involved in transcription and translation. Other aspects of archaeal biochemistry are unique, such as their reliance on ether lipids in their cell membranes,[7] including archaeols. Archaea use more diverse energy sources than eukaryotes, ranging from organic compounds such as sugars, to ammonia, metal ions or even hydrogen gas. The salt-tolerantHaloarchaea use sunlight as an energy source, and other species of archaea fix carbon (autotrophy), but unlike cyanobacteria, no known species of archaea does both. Archaea reproduce asexually by binary fission, fragmentation, or budding; unlike bacteria, no known species of Archaea form endospores. A few archaea have shapes, such as the flat, square cells of Haloquadratum walsbyi, that are very different from bacteria. The first observed archaea were extremophiles, living in extreme environments such as hot springs and salt lakes with no other organisms. Improved molecular detection tools led to the discovery of archaea in almost every habitat, including soil,[8]oceans, and marshlands. Archaea are particularly numerous in the oceans, and the archaea in plankton may be one of the most abundant groups of organisms on the planet.

Archaea are a major part of Earth's life. They are part of the microbiota of all organisms. In the human microbiome, they are important in the gut, mouth, and on the skin.[9] Their morphological, metabolic, and geographical diversity permits them to play multiple ecological roles: carbon fixation; nitrogen cycling; organic compound turnover; and maintaining microbial symbiotic and syntrophic communities, for example.[8][10]

No clear examples of archaeal pathogens or parasites are known. Instead they are often mutualists or commensals, such as the methanogens (methane-producing strains) that inhabit the gastrointestinal tract in humans and ruminants, where their vast numbers facilitate digestion. Methanogens are also used in biogas production and sewage treatment, and biotechnology exploits enzymes from extremophile archaea that can endure high temperatures and organic solvents.

Classification of Archaea is difficult because most species have not been isolated in a laboratory and have been detected only by their gene sequences in environmental samples. Traditionally, Archaea only included its prokaryotic members, but this since has been found to be paraphyletic, as eukaryotes are now known to have evolved from archaea. Archaea were initially classified as bacteria, receiving the name archaebacteria (/ˌɑːrkibækˈtɪəriə/, in the Archaebacteria kingdom), but this term has fallen out of use.[5]

T g7 (talk) 21:41, 28 January 2025 (UTC)

Usage of The Template Paraphyletic Group Instead of Automatic Taxobox

I think we should use the paraphyletic group template instead of automatic taxobox as Archaea doesn't include Eukarya. Jako96 (talk) 12:53, 2 April 2025 (UTC)

You'll see from the thread(s) above that this is not a neutral proposal. Chiswick Chap (talk) 15:18, 2 April 2025 (UTC)

Yeah, you are right. Jako96 (talk) 16:18, 2 April 2025 (UTC)

Names for the images in the lead collage

I was wondering if somebody could add a caption with names for each sample in the collage image in the lead.

It's not terribly helpful to provide a sampling of archaea when it doesn't give their names. It would be more useful as a resource if it provided names. That way a user can look them up for themselves and learn more about them than what they look like subjectively.

Thank you VoidHalo (talk) 12:51, 29 April 2025 (UTC)

Done. =) CheckNineEight (talk) 07:33, 12 May 2025 (UTC)

Why didn't we use the paraphyletic group template for archaeans and why didn't we put eukaryotes under "Cladistically included but traditionally excluded taxa"?

Archaeans are a paraphyletic group, and eukaryotes are cladistically included in archaeans but traditionally excluded from archaeans Cantthinkofanyusername (talk) 05:53, 3 April 2026 (UTC)

I also agree with this, there is no reason NOT to use that template here. @Grmanners and @Kiwi Rex, do you also agree with us here? Since you also agreed to use the same template in Reptile. Jako96 (talk) 13:38, 12 April 2026 (UTC)

There's an inconvenient aspect: Archaea was recently transformed into a formal Linnaean taxon regulated by a Code but the relevant proposals do not discuss how eukaryote taxonomy fits into this - and none of the eukaryote codes regulate domains. The Catalogue of Life currently has the usual three domains (+viruses) with the various new prokaryotic kingdoms - but Wikipedia doesn't follow the CoL. I think the general perception of archaea as the third "kind" of organism that is neither eukaryotic nor bacterial makes the template appropriate for now, and it also fits Asgard archaea (more straightforwardly) Kiwi Rex (talk) 21:52, 12 April 2026 (UTC)

Sorry, the is well out of my knowledge and comfort zones, so I cannot comment—GRM (talk) 08:38, 23 April 2026 (UTC)