Red algae 341045 224819300 2008-07-10T15:40:56Z 72.65.176.176 /* Reproduction */ {{Taxobox | color = lightgreen | name = Red algae | image = Laurencia.jpg | image_width = 240px | domain = [[Eukaryota]] | unranked_phylum = [[Archaeplastida]] | phylum = '''Rhodophyta''' | phylum_authority = [[Richard Wettstein|Wettstein]], 1922 | subdivision_ranks = Class | subdivision = *[[Rhodophyceae]] (There were formerly thought to be two classes, [[Florideophyceae]] and [[Bangiophyceae]].)<ref name=Lee2008>{{citation|author=Lee, R.E.|title=Phycology, 4th edition|year=2008|isbn= 978-0521638838|publisher= Cambridge University Press}}</ref> }} The '''red algae''' (Rhodophyta, {{IPAEng|ˌroʊdəˈfaɪtə, roʊˈdɒfɨtə}}, from [[Greek language|Greek]]: ''{{Unicode|ῥόδον}} (rhodon)'' = rose + ''{{Unicode|φυτόν}} (phyton)'' = plant, thus red plant) are one of the oldest groups of eukaryotic algae,<ref name=Lee2008>{{citation|author=lee, R.E.|title=Phycology, 4th edition|year=2008|isbn= 978-0521638838|publisher= Cambridge University Press}}</ref>, and also one of the largest, with about 5,000–6,000 species&nbsp;<ref name="Thomas 02">{{cite book |author=D. Thomas |year=2002 |title=Seaweeds |publisher=Life Series. [[Natural History Museum]], London |id=ISBN 0-565-09175-1}}</ref> of mostly [[multicellular]], [[ocean|marine]] [[algae]], including many notable [[seaweed]]s. Other references indicate 10,000 species.&nbsp;<ref name="Woelkerling 90">{{cite book |author=W. J. Woelkerling |chapter=An introduction |editor=K. M. Cole & R. G. Sheath |year=1990 |title=Biology of the Red Algae |publisher=[[Cambridge University Press]], Cambridge |id=ISBN 0-521-34301-1 |pages=1–6}}</ref> Most of the [[coralline algae]], which secrete [[calcium carbonate]] and play a major role in building [[coral reef]]s, belong here. Red algae such as [[dulse]] ''(Palmaria palmata)'' and [[laver (seaweed)|laver]] ([[nori]]/[[Gim (Korean food)|gim]]) are a traditional part of [[Europe]]an and [[Asia]]n cuisine and are used to make other products like [[agar]], [[carrageenan]]s and other [[food additives]].&nbsp;<ref name="Guiry">{{cite web |url=http://www.seaweed.ie/algae/rhodophyta.lasso |title=Rhodophyta: red algae |author=M. D. Guiry |Publisher=[National University of Ireland, Galway]] |accessdate=2007-06-28}}</ref> [[Image:Seagrass at california tide pools.jpg|thumb|left|250px|A red alga in a [[California]] [[tide pool]] displaying some [[iridescence]] when not covered with water]] ==Fossil record==<!-- This section is linked from [[Eukaryote]] --> The oldest fossil identified as a red alga is also the oldest fossil [[eukaryote]] that belongs to a specific modern [[taxon]]. ''Bangiomorpha pubescens'', a multicellular fossil from arctic [[Canada]], strongly resembles the modern red alga ''Bangia'' despite occurring in rocks dating to 1200 million years ago.&nbsp;<ref name="butterfield">{{cite journal |quotes=no |author=N. J. Butterfield |year=2000 |title=''Bangiomorpha pubescens'' n. gen., n. sp.: implications for the evolution of sex, multicellularity, and the Mesoproterozoic/Neoproterozoic radiation of eukaryotes |journal=[[Paleobiology (journal)|Paleobiology]] |volume=26 |issue=3 |pages=386–404 |url=http://paleobiol.geoscienceworld.org/cgi/content/abstract/26/3/386 |doi=10.1666/0094-8373(2000)026<0386:BPNGNS>2.0.CO;2}}</ref> Red algae are important builders of limestone reefs. The earliest such [[coralline algae]], the solenopores, are known from the [[Cambrian]] Period. Other algae of different origins filled a similar role in the late [[Paleozoic]], and in more recent reefs. ==Taxonomy== The red algae are classified in the [[Archaeplastida]], along with the [[glaucophyte]]s and [[Viridiplantae]] (green algae and land plants). Below are two valid published taxonomies of the red algae, although neither necessarily has to be used, as the taxonomy of the algae is still in a state of flux (with classification above the level of [[Order (biology)|order]] having received little scientific attention for most of the 20th century).<ref name="saunders">{{cite journal |quotes=no |author=G. W. Saunders & M. H. Hommersand |year=2004 |title=Assessing red algal supraordinal diversity and taxonomy in the context of contemporary systematic data |journal=[[American Journal of Botany]] |volume=91 |pages=1494–1507 |doi=}}</ref> If one defines the kingdom Plantae to mean the Archaeplastida, the red algae will be part of that kingdom; but if Plantae are defined more narrowly, to be the Viridiplantae, then the red algae might be considered their own kingdom<ref name="saunders"/> or part of the kingdom [[Protista]]. The two classification systems below place the red algae in the plant kingdom. {| class="wikitable" !According to synthesis in Lee (2008)<ref name=Lee2008/> !'''Classification system according to<br>Hwan Su Yoon et al. 2006<ref name="yoon">{{cite journal |quotes=no |author=Hwan Su Yoon, K. M. Müller, R. G. Sheath, F. D. Ott & D. Bhattacharya |year=2006 |title=Defining the major lineages of red algae (Rhodophyta) |url=http://www.biology.uiowa.edu/debweb/downloads/Files/Yoon%20et%20al%20J%20Phycol%2006.pdf |doi=10.1111/j.1529-8817.2006.00210.x |journal=[[Journal of Phycology]]|volume=42 |pages=482–492}}</ref> !'''Classification system according to<br>Saunders and Hommersand 2004<ref name="saunders"/> |- ||Domain Eukaryota (Corticata) *Kingdom [[Chromalveolata]] <small>Cavalier-Smith, 1998</small> **Phylum Rhodophyta ***Class Rhodophytina ****Orders ***** Cyanidiales ***** Porphyridiales ***** Bangiales ***** Acrochaetiales ***** Batrachospermales ***** Nemaliales ***** Corallinales ***** Gelidiales ***** Gracilariales ***** Ceramiales ||Kingdom [[Plant]]ae <small>Haeckel</small> * Subkingdom [[Biliphyta]] <small>Wettstein</small> ** Phylum [[Rhodophyta]] <small>Wettstein</small> ***Subphylum [[Cyanidiophytina]] ''subphylum novus'' **** Class [[Cyanidiophyceae]] <small>Merola et al</small> *** Subphylum [[Rhodophytina]] ''subphylum novus'' **** Class [[Bangiophyceae]] <small>Wettstein</small> **** Class [[Compsopogonophyceae]] <small>Saunders et Hommersand</small> **** Class [[Florideophyceae]] <small>Cronquist</small> **** Class [[Porphyridiophyceae]] ''classis nova'' **** Class [[Rhodellophyceae]] <small>Cavalier-Smith</small> **** Class [[Stylonematophyceae]] ''classis nova'' ||Kingdom [[Plant]]ae <small>Haeckel</small> * Subkingdom [[Rhodoplantae]] ** Phylum [[Cyanidiophyta]] *** Class [[Cyanidiophyceae]] <small>Merola et al</small> ** Phylum [[Rhodophyta]] <small>Wettstein</small> *** Subphylum [[Rhodellophytina]] **** Class [[Rhodellophyceae]] <small>Cavalier-Smith</small> *** Subphylum [[Metarhodophytina]] **** Class [[Compsopogonophyceae]] <small>Saunders et Hommersand</small> *** Subphylum [[Eurhodophytina]] **** Class [[Bangiophyceae]] <small>Wettstein</small> **** Class [[Florideophyceae]] <small>Cronquist</small> ***** Subclass [[Hildenbrandiophycidae]] ***** Subclass [[Nemaliophycidae]] ***** Subclass [[Ahnfeltiophycidae]] ***** Subclass [[Rhodymeniophycidae]] |} ==Species of red algae== There are around 6,500 to 10,000 known species,&nbsp;<ref name="Woelkerling 90"/><ref name="Guiry"/> nearly all of which are marine, with about 200 that only live in [[fresh water]]. However estimates of the number of real species vary by 100%.&nbsp;<ref name="Woelkerling 90"/> Some examples of species and genera of red algae are: *''[[Atractophora hypnoides]]'' *''[[Gelidiella calcicola]]'' *''[[Lemanea]]'', a freshwater genus *''[[Palmaria palmata]]'', dulse *''[[Schmitzia hiscockiana]]'' *''[[Chondrus crispus]]'', Irish moss *''[[Mastocarpus stellatus]]'' ==Pit connections and pit plugs== {{main|Pit connection}} ===Pit connections=== Pit connections and pit plugs are unique and distinctive features of red algae that form during the process of [[cytokinesis]] following mitosis. In red algae, cytokinesis is incomplete. Typically, a small pore is left in the middle of the newly formed partition. The pit connection is formed where the daughter cells remain in contact. Shortly after the pit connection is formed cytoplasmic continuity is blocked by the generation of a pit plug, which is deposited in the wall gap that connects the cells. Connections between cells having a common parent cell are called a primary pit connections. Because apical growth is the norm in red algae, most cells have two primary pit connections, one to each adjacent cell. Connections that exist between cells not sharing a common parent cells are labeled secondary pit connections. These connections are formed when an unequal cell division produced a nucleated daughter cell that then fuses to an adjacent cell. Patterns of secondary pit connections can be seen in the order Ceramiales. ===Pit plugs=== After a pit connection is formed, tubular membranes appear. A granular protein, called the plug core, then forms around the membranes. The tubular membranes eventually disappear. While some orders of red algae simply have a plug core, others have an associated membrane at each side of the protein mass, called cap membranes. The pit plug continues to exist between the cells until one of the cells dies. When this happens, the living cell produce a layer of wall material that seals off the plug. ===Function=== It is thought that the pit connections function as structural reinforcement, and as an avenue for cell to cell communication and/or symplastic transport in red algae.{{Fact|date=April 2007}} While the presence of the cap membrane could inhibit this transport between cells, it has been hypothesized that the tubular plug cores serve as a means of transport. ==Reproduction== Red algae lack motile sperm. Hence they rely on water currents to transport their gametes to the female organs.<ref name=Lee2008>{{citation|author=Lee, R.E.|title=Phycology, 4th edition|year=2008|isbn= 978-0521638838|publisher= Cambridge University Press}}</ref> They display [[alternation of phases]]; as well as a gametophyte phase, many have two sporophyte phases, the carposporophyte producing carpospores, which germinate into a tetrasporophyte - this produces spore tetrads, which dissociate and germinate into gametophytes.<ref name=Lee2008>{{citation|author=Lee, R.E.|title=Phycology, 4th edition|year=2008|isbn= 978-0521638838|publisher= Cambridge University Press}}</ref> ==Human Consumption== Several species are used as food. [[Dulse]] (''[[Palmaria palmata]]'')<ref>{{cite web |url=http://www.seaveg.co.uk/dulse.html |publisher=Quality Sea Veg |title=Dulse: ''Palmaria palmata'' |accessdate=2007-06-28}}</ref> and ''[[Porphyra]]'' are the best known in the British Isles.&nbsp;<ref>{{cite book |author=T. F. Mumford & A. Muira |chapter=''Porphyra'' as food: cultivation and economics |title=Algae and Human Affairs |editor=C. A. Lembi & J. Waaland |year=1988 |publisher=[[Cambridge University Press]], Cambridge |id=ISBN 0-521-32115-8}}</ref> In East and Southeast Asia, agar is most commonly produced from ''[[Gelidium amansii]]''. ==See also== *[[Brown algae]] *[[Green algae]] *[[Red tide]] (red tides are caused by algae from the phylum ''Dinoflagellata,'' and not red algae [''Rhodophyta'']) *[[Françoise Ardré]] (namesake of the red alga known as ''Pterosiphonia ardreana'') ==References== {{reflist}} ==External links== *[http://www.mbari.org/staff/conn/botany/flora/reds.htm Monterey Bay Flora] *[http://www.rbgsyd.nsw.gov.au/information_about_plants/botanical_info/aussie_marine_algae/life_cycle Life cycle of red algae] [[Category:Protista]] [[Category:Algae]] [[Category:Red algae| ]] [[bg:Червени водорасли]] [[ca:Alga vermella]] [[cs:Ruduchy]] [[da:Rødalger]] [[de:Rotalgen]] [[et:Punavetiktaimed]] [[es:Rhodophyta]] [[fr:Rhodophyta]] [[gl:Algas vermellas]] [[id:Ganggang merah]] [[it:Rhodophyta]] [[he:אדומיות]] [[ka:ძოწეული წყალმცენარეები]] [[lt:Raudondumbliai]] [[hu:Vörösmoszatok]] [[mk:Црвени алги]] [[ja:紅藻]] [[no:Rødalger]] [[nds:Rhodophyta]] [[pl:Krasnorosty]] [[pt:Rhodophyta]] [[ru:Красные водоросли]] [[sk:Červené riasy]] [[sl:Rdeče alge]] [[sr:Црвене алге]] [[sh:Crvene alge]] [[fi:Punalevät]] [[sv:Rödalger]] [[vi:Tảo đỏ]] [[tr:Kırmızı algler]] [[zh:紅藻]]