Editing Algae (section)

==Numbers==
[[File:Taiwan 2009 East Coast ShihTiPing Giant Stone Steps Algae FRD 6581.jpg|thumb|Algae on coastal rocks at [[:zh:石梯坪|Shihtiping]] in [[Taiwan]]]]
The ''Algal Collection of the US National Herbarium'' (located in the [[National Museum of Natural History]]) consists of approximately 320,500 dried specimens, which, although not exhaustive (no exhaustive collection exists), gives an idea of the order of magnitude of the number of algal species (that number remains unknown).<ref>{{cite web |title=Algae Herbarium |publisher=National Museum of Natural History, Department of Botany |year=2008 |url= http://botany.si.edu/projects/algae/herbarium.htm |access-date=19 December 2008 |archive-url= https://web.archive.org/web/20081201112552/http://botany.si.edu/projects/algae/herbarium.htm |archive-date=1 December 2008 |url-status=live}}</ref> Estimates vary widely. For example, according to one standard textbook,<ref>John (2002), p. 1.</ref> in the [[British Isles]], the ''UK Biodiversity Steering Group Report'' estimated there to be 20,000 algal species in the UK. Another checklist reports only about 5,000 species. Regarding the difference of about 15,000 species, the text concludes: "It will require many detailed field surveys before it is possible to provide a reliable estimate of the total number of species&nbsp;..."

Regional and group estimates have been made, as well:
* 5,000–5,500 species of red algae worldwide
* "some 1,300 in Australian Seas"<ref>Huisman (2000), p. 25.</ref>
* 400 seaweed species for the western coastline of South Africa,<ref>Stegenga (1997).</ref> and 212 species from the coast of KwaZulu-Natal.<ref>{{cite book |last=Clerck |first=Olivier |title=Guide to the seaweeds of KwaZulu-Natal |date=2005 |publisher=National Botanic Garden of Belgium |isbn=978-90-72619-64-8}}</ref> Some of these are duplicates, as the range extends across both coasts, and the total recorded is probably about 500 species. Most of these are listed in [[List of seaweeds of South Africa (disambiguation)|List of seaweeds of South Africa]]. These exclude [[phytoplankton]] and crustose corallines.
* 669 marine species from California (US)<ref>Abbott and Hollenberg (1976), p. 2.</ref>
* 642 in the check-list of Britain and Ireland<ref>Hardy and Guiry (2006).</ref>
and so on, but lacking any scientific basis or reliable sources, these numbers have no more credibility than the British ones mentioned above. Most estimates also omit microscopic algae, such as phytoplankton.

The most recent estimate (as of the beginning of 2024) suggests 50,589 recent and 10,556 fossil algal species, generally classified into 14 traditional phyla/divisions (other representatives such as ''incertae sedis'', etc.):<ref name="Guiry-2024"/>
{| class="wikitable"
![[phylum]] ([[division]])
!'''number of described [[genus|genera]]'''
!'''number of described [[species]]'''
|-
|"Charophyta" ([[Streptophyta]] without [[embryophyte|land plants]])||style="text-align:right" |236||style="text-align:right" |5&nbsp;644
|-
|[[Chlorophyta]] ''([[Stricto sensu|s.s.]])''||style="text-align:right" |1&nbsp;513||style="text-align:right" |7&nbsp;934
|-
|Chromeridophyta ([[Chromera velia|Chromerida]])||style="text-align:right" |6||style="text-align:right" |8
|-
|[[Cryptophyta]] (Cryptista ''[[Stricto sensu|s.s.]]'')||style="text-align:right" |44||style="text-align:right" |245
|-
|[[Cyanobacteriota]] ([[Cyanophyta]])||style="text-align:right" |866||style="text-align:right" |5&nbsp;723
|-
|[[Dinoflagellata]] ([[Dinophyta]], Dinozoa)||style="text-align:right" |710||style="text-align:right" |3&nbsp;911
|-
|Euglenophyta ([[Euglenozoa]])||style="text-align:right" |164||style="text-align:right" |2&nbsp;057
|-
|[[Glaucophyta]]||style="text-align:right" |8||style="text-align:right" |25
|-
|[[Haptophyta]]||style="text-align:right" |391||style="text-align:right" |1&nbsp;722
|-
|[[Heterokontophyta]] ([[Ochrophyta]])||style="text-align:right" |1&nbsp;781||style="text-align:right" |23&nbsp;314
|-
|Picophyta ([[Picozoa]])||style="text-align:right" |1||style="text-align:right" |1
|-
|[[Prasinodermatophyta]] ([[Prasinodermophyta]])||style="text-align:right" |5||style="text-align:right" |10
|-
|Rhodelphidophyta ([[Rhodelphidia]])||style="text-align:right" |1||style="text-align:right" |2
|-
|[[Rhodophyta]] ||style="text-align:right" |1094||style="text-align:right" |7554
|-
|''[[Incertae sedis]]'' etc.||style="text-align:right" |887||style="text-align:right" |2&nbsp;995
|-
|'''Total'''||style="text-align:right" |'''7&nbsp;707'''||style="text-align:right" |'''61&nbsp;145'''
|}