59-541: Cyanidiaceae is a family of red algae , one of two families in the Division Cyanidiophytina . This Rhodophyta -related article is a stub . You can help Misplaced Pages by expanding it . Red algae Red algae , or Rhodophyta ( / r oʊ ˈ d ɒ f ɪ t ə / , / ˌ r oʊ d ə ˈ f aɪ t ə / ; from Ancient Greek ῥόδον ( rhódon ) 'rose' and φυτόν ( phutón ) 'plant'), make up one of
118-469: A and d . Red algae are red due to phycoerythrin . They contain the sulfated polysaccharide carrageenan in the amorphous sections of their cell walls, although red algae from the genus Porphyra contain porphyran . They also produce a specific type of tannin called phlorotannins , but in a lower amount than brown algae do. As enlisted in realDB , 27 complete transcriptomes and 10 complete genomes sequences of red algae are available. Listed below are
177-453: A and phycobiliproteins , like most cyanobacteria, and accumulate starch outside the chloroplasts. The green algae and land plants – together known as Viridiplantae (Latin for "green plants") or Chloroplastida – are pigmented with chlorophylls a and b , but lack phycobiliproteins, and starch is accumulated inside the chloroplasts. The glaucophytes have typical cyanobacterial pigments, but their plastids (called cyanelles) differ in having
236-399: A tetrasporophyte – this produces spore tetrads, which dissociate and germinate into gametophytes. The gametophyte is typically (but not always) identical to the tetrasporophyte. Carpospores may also germinate directly into thalloid gametophytes, or the carposporophytes may produce a tetraspore without going through a (free-living) tetrasporophyte phase. Tetrasporangia may be arranged in
295-407: A 150 ug/day requirement of iodine is obtained from a single gram of red algae. Red algae, like Gracilaria , Gelidium , Euchema , Porphyra , Acanthophora , and Palmaria are primarily known for their industrial use for phycocolloids (agar, algin, furcellaran and carrageenan) as thickening agent, textiles, food, anticoagulants, water-binding agents, etc. Dulse ( Palmaria palmata )
354-607: A broad sense"; pronounced / ɑːr k ɪ ˈ p l æ s t ɪ d ə / ) are a major group of eukaryotes , comprising the photoautotrophic red algae (Rhodophyta), green algae , land plants , and the minor group glaucophytes . It also includes the non-photosynthetic lineage Rhodelphidia , a predatorial (eukaryotrophic) flagellate that is sister to the Rhodophyta, and probably the microscopic picozoans . The Archaeplastida have chloroplasts that are surrounded by two membranes, suggesting that they were acquired directly through
413-482: A carbon source have less negative δ C values than those that only use CO 2 . An additional difference of about 1.71‰ separates groups intertidal from those below the lowest tide line, which are never exposed to atmospheric carbon. The latter group uses the more C-negative CO 2 dissolved in sea water, whereas those with access to atmospheric carbon reflect the more positive signature of this reserve. Photosynthetic pigments of Rhodophyta are chlorophylls
472-436: A double membrane, lack grana and phycobilisomes on the stromal surface of the thylakoid membrane. The major photosynthetic products include floridoside (major product), D‐isofloridoside, digeneaside, mannitol, sorbitol, dulcitol etc. Floridean starch (similar to amylopectin in land plants), a long-term storage product, is deposited freely (scattered) in the cytoplasm. The concentration of photosynthetic products are altered by
531-514: A few species can reach lengths of 2 m. In the SCRP clade the class Compsopogonophyceae is multicellular, with forms varying from microscopic filaments to macroalgae. Stylonematophyceae have both unicellular and small simple filamentous species, while Rhodellophyceae and Porphyridiophyceae are exclusively unicellular. Most rhodophytes are marine with a worldwide distribution, and are often found at greater depths compared to other seaweeds. While this
590-482: A parasitic lifestyle and may be found on closely or more distantly related red algal hosts. In the classification system of Adl et al. 2005, the red algae are classified in the Archaeplastida , along with the glaucophytes and the green algae plus land plants ( Viridiplantae or Chloroplastida). The authors use a hierarchical arrangement where the clade names do not signify rank; the class name Rhodophyceae
649-493: A peptidoglycan outer layer. Archaeplastida should not be confused with the older and obsolete name Archiplastideae, which refers to cyanobacteria and other groups of bacteria. The consensus in 2005, when the group consisting of the glaucophytes and red and green algae and land plants was named 'Archaeplastida', was that it was a clade , i.e. was monophyletic . Many studies published since then have provided evidence in agreement. Other studies, though, have suggested that
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#1732802471884708-415: 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,
767-568: A row ( zonate ), in a cross (cruciate), or in a tetrad. The carposporophyte may be enclosed within the gametophyte, which may cover it with branches to form a cystocarp . The two following case studies may be helpful to understand some of the life histories algae may display: In a simple case, such as Rhodochorton investiens : A rather different example is Porphyra gardneri : The δ C values of red algae reflect their lifestyles. The largest difference results from their photosynthetic metabolic pathway : algae that use HCO 3 as
826-399: A single endosymbiosis event by phagocytosis of a cyanobacterium . All other groups which have chloroplasts, besides the amoeboid genus Paulinella , have chloroplasts surrounded by three or four membranes, suggesting they were acquired secondarily from red or green algae. Unlike red and green algae, glaucophytes have never been involved in secondary endosymbiosis events. The cells of
885-481: A single origin. This evidence is disputed. Based on the evidence to date, it is not possible to confirm or refute alternative evolutionary scenarios to a single primary endosymbiosis . Photosynthetic organisms with plastids of different origin (such as brown algae ) do not belong to the Archaeplastida. The archaeplastidans fall into two main evolutionary lines. The red algae are pigmented with chlorophyll
944-405: A traditional part of European and Asian cuisines and are used to make products such as agar , carrageenans , and other food additives . Chloroplasts probably evolved following an endosymbiotic event between an ancestral, photosynthetic cyanobacterium and an early eukaryotic phagotroph . This event (termed primary endosymbiosis ) is at the origin of the red and green algae (including
1003-507: A worldwide distribution in various habitats; they generally prefer clean, high-flow streams with clear waters and rocky bottoms, but with some exceptions. A few freshwater species are found in black waters with sandy bottoms and even fewer are found in more lentic waters. Both marine and freshwater taxa are represented by free-living macroalgal forms and smaller endo/epiphytic/zoic forms, meaning they live in or on other algae, plants, and animals. In addition, some marine species have adopted
1062-526: Is Plastida, defined as the clade sharing "plastids of primary (direct prokaryote) origin [as] in Magnolia virginiana Linnaeus 1753". Although many studies have suggested the Archaeplastida form a monophyletic group, a 2009 paper argues that they are in fact paraphyletic . The enrichment of novel red algal genes in a recent study demonstrates a strong signal for Plantae (Archaeplastida) monophyly and an equally strong signal of gene sharing history between
1121-823: Is estimated that more than half of all known species of microbial eukaryotes harbor red-alga-derived plastids. Red algae are divided into the Cyanidiophyceae , a class of unicellular and thermoacidophilic extremophiles found in sulphuric hot springs and other acidic environments, an adaptation partly made possible by horizontal gene transfers from prokaryotes, with about 1% of their genome having this origin, and two sister clades called SCRP ( Stylonematophyceae , Compsopogonophyceae , Rhodellophyceae and Porphyridiophyceae ) and BF ( Bangiophyceae and Florideophyceae ), which are found in both marine and freshwater environments. The BF are macroalgae, seaweed that usually do not grow to more than about 50 cm in length, but
1180-452: 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 primary pit connections. Because apical growth
1239-726: Is one of the most consumed red algae and is a source of iodine, protein, magnesium and calcium. Red algae's nutritional value is used for the dietary supplement of algas calcareas . China, Japan, Republic of Korea are the top producers of seaweeds. In East and Southeast Asia, agar is most commonly produced from Gelidium amansii . These rhodophytes are easily grown and, for example, nori cultivation in Japan goes back more than three centuries. Researchers in Australia discovered that limu kohu ( Asparagopsis taxiformis ) can reduce methane emissions in cattle . In one Hawaii experiment,
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#17328024718841298-528: Is supported by various structural and genetic similarities. Red algae have a long history of use as a source of nutritional, functional food ingredients and pharmaceutical substances. They are a source of antioxidants including polyphenols, and phycobiliproteins and contain proteins, minerals, trace elements, vitamins and essential fatty acids. Traditionally, red algae are eaten raw, in salads, soups, meal and condiments. Several species are food crops, in particular dulse ( Palmaria palmata ) and members of
1357-419: Is the isopod Idotea balthica. The trichogyne will continue to grow until it encounters a spermatium ; once it has been fertilized, the cell wall at its base progressively thickens, separating it from the rest of the carpogonium at its base. Upon their collision, the walls of the spermatium and carpogonium dissolve. The male nucleus divides and moves into the carpogonium; one half of the nucleus merges with
1416-426: 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 cell are labelled 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 . After
1475-446: Is used for the red algae. No subdivisions are given; the authors say, "Traditional subgroups are artificial constructs, and no longer valid." Many subsequent studies provided evidence that is in agreement for monophyly in the Archaeplastida (including red algae). However, other studies have suggested Archaeplastida is paraphyletic . As of January 2011 , the situation appears unresolved. Below are other published taxonomies of
1534-510: The Ediacaran Period. Thallophytes resembling coralline red algae are known from the late Proterozoic Doushantuo formation . Chromista and Alveolata algae (e.g., chrysophytes, diatoms, phaeophytes, dinophytes) seem to have evolved from bikonts that have acquired red algae as endosymbionts . According to this theory, over time these endosymbiont red algae have evolved to become chloroplasts. This part of endosymbiotic theory
1593-412: The eukaryotes which took into account morphology, biochemistry, and phylogenetics, and which had "some stability in the near term." They rejected the use of formal taxonomic ranks in favour of a hierarchical arrangement where the clade names do not signify rank. Thus, the phylum name 'Glaucophyta' and the class name 'Rhodophyceae' appear at the same level in their classification. The divisions proposed for
1652-706: The 10 complete genomes of red algae. One of the oldest fossils 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 and occurs in rocks dating to 1.05 billion years ago. Two kinds of fossils resembling red algae were found sometime between 2006 and 2011 in well-preserved sedimentary rocks in Chitrakoot, central India. The presumed red algae lie embedded in fossil mats of cyanobacteria, called stromatolites, in 1.6 billion-year-old Indian phosphorite – making them
1711-557: The Archaeplastida are shown below in both tabular and diagrammatic form . Archaeplastida : Below is a consensus reconstruction of the relationships of Archaeplastida with its nearest neighbours, mainly based on molecular data. Hemimastigophora [REDACTED] Provora Haptista [REDACTED] Telonemia Rhizaria [REDACTED] Stramenopiles [REDACTED] Alveolata [REDACTED] Cryptista [REDACTED] Microheliella maris Archaeplastida [REDACTED] There has been disagreement near
1770-527: The Archaeplastida root, e.g. whether Cryptista emerged within the Archaeplastida. In 2014 a thorough review was published on these inconsistencies. The position of Telonemia and Picozoa are not clear. Also Hacrobia (Haptista + Cryptista) may be completely associated with the SAR clade. The SAR are often seen as eukaryote-eukaryote hybrids, contributing to the confusion in the genetic analyses. A sister of Gloeomargarita lithophora has been engulfed by an ancestor of
1829-407: The Archaeplastida typically lack centrioles and have mitochondria with flat cristae . They usually have a cell wall that contains cellulose , and food is stored in the form of starch . However, these characteristics are also shared with other eukaryotes. The main evidence that the Archaeplastida form a monophyletic group comes from genetic studies, which indicate their plastids probably had
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1888-471: The Archaeplastida, leading to the plastids which are living in permanent endosymbiosis in most of the descendant lineages. Because both Gloeomargarita and related cyanobacteria, in addition to the most primitive archaeplastids, all live in freshwater, it seems the Archaeplastida originated in freshwater, and only colonized the oceans in the late Proterozoic. In 2019, a phylogeny of the Archaeplastida based on genomes and transcriptomes from 1,153 plant species
1947-576: The Assembling the Tree of Life Program. Porphyridiales Bangiales Some sources (such as Lee) place all red algae into the class "Rhodophyceae". (Lee's organization is not a comprehensive classification, but a selection of orders considered common or important. ) A subphylum - Proteorhodophytina - has been proposed to encompass the existing classes Compsopogonophyceae , Porphyridiophyceae , Rhodellophyceae and Stylonematophyceae . This proposal
2006-468: The absence of chloroplast endoplasmic reticulum. The presence of the water-soluble pigments called phycobilins ( phycocyanobilin , phycoerythrobilin , phycourobilin and phycobiliviolin ), which are localized into phycobilisomes , gives red algae their distinctive color. Their chloroplasts contain evenly spaced and ungrouped thylakoids and contain the pigments chlorophyll a, α- and β-carotene, lutein and zeaxanthin. Their chloroplasts are enclosed in
2065-751: The asexual class Cyanidiophyceae , no terrestrial species exist, which may be due to an evolutionary bottleneck in which the last common ancestor lost about 25% of its core genes and much of its evolutionary plasticity. Red algae form a distinct group characterized by eukaryotic cells without flagella and centrioles , chloroplasts without external endoplasmic reticulum or unstacked (stroma) thylakoids , and use phycobiliproteins as accessory pigments , which give them their red color. Despite their name, red algae can vary in color from bright green, soft pink, resembling brown algae, to shades of red and purple, and may be almost black at greater depths. Unlike green algae, red algae store sugars as food reserves outside
2124-430: The bacterium, and the other to the eukaryote that captured it. Over time, many genes from the chloroplast have been transferred to the nucleus of the host cell through endosymbiotic gene transfer (EGT). It is estimated that 6–20% of the archaeplastidan genome consist of genes transferred from the endosymbiont. The presence of such genes in the nuclei of eukaryotes without chloroplasts suggests this transfer happened early in
2183-404: The carpogonium's nucleus. The polyamine spermine is produced, which triggers carpospore production. Spermatangia may have long, delicate appendages, which increase their chances of "hooking up". They display alternation of generations . In addition to a gametophyte generation, many have two sporophyte generations, the carposporophyte -producing carpospores , which germinate into
2242-541: The chloroplasts as floridean starch , a type of starch that consists of highly branched amylopectin without amylose . Most red algae are multicellular , macroscopic, and reproduce sexually . The life history of red algae is typically an alternation of generations that may have three generations rather than two. Coralline algae , which secrete calcium carbonate and play a major role in building coral reefs , belong there. Red algae such as Palmaria palmata (dulse) and Porphyra species ( laver / nori / gim ) are
2301-473: The degree of their cell organization, from isolated cells to filaments to colonies to multi-celled organisms. The earliest were unicellular, and many groups remain so today. Multicellularity evolved separately in several groups, including red algae, ulvophyte green algae , and in the green algae that gave rise to stoneworts and land plants. Because the ancestral archaeplastidan is hypothesized to have acquired its chloroplasts directly by engulfing cyanobacteria,
2360-441: The environmental conditions like change in pH, the salinity of medium, change in light intensity, nutrient limitation etc. When the salinity of the medium increases the production of floridoside is increased in order to prevent water from leaving the algal cells. 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
2419-419: The event is known as a primary endosymbiosis (as reflected in the name chosen for the group 'Archaeplastida' i.e. 'ancient plastid'). In 2013 it was discovered that one species of green algae, Cymbomonas tetramitiformis in the order Pyramimonadales , is a mixotroph and able to support itself through both phagotrophy and phototrophy . It is not yet known if this is a primitive trait and therefore defines
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2478-438: The genus Porphyra , variously known as nori (Japan), gim (Korea), zicai 紫菜 (China), and laver (British Isles). Red algal species such as Gracilaria and Laurencia are rich in polyunsaturated fatty acids (eicopentaenoic acid, docohexaenoic acid, arachidonic acid ) and have protein content up to 47% of total biomass. Where a big portion of world population is getting insufficient daily iodine intake,
2537-409: The group is paraphyletic . To date, the situation appears unresolved, but a strong signal for Plantae (Archaeplastida) monophyly has been demonstrated in a recent study (with an enrichment of red algal genes). The assumption made here is that Archaeplastida is a valid clade. Various names have been given to the group. Some authors have simply referred to the group as plants or Plantae. However,
2596-995: The hornwort genomes that have also since been sequenced. Recent work on non-photosynthetic algae places Rhodelphidia as sister to Rhodophyta or to Glaucophyta and Viridiplantae; and Picozoa sister to that pair of groups. Picozoa [REDACTED] Rhodelphidia Rhodophyta [REDACTED] Glaucophyta [REDACTED] Chlorophyta [REDACTED] Prasinococcales Mesostigmatophyceae Chlorokybophyceae Spirotaenia [REDACTED] Klebsormidiales [REDACTED] Chara [REDACTED] Coleochaetales Zygnematophyceae [REDACTED] Hornworts [REDACTED] Liverworts [REDACTED] Mosses [REDACTED] Lycophytes [REDACTED] Ferns [REDACTED] Gymnosperms [REDACTED] Angiosperms [REDACTED] All archaeplastidans have plastids (chloroplasts) that carry out photosynthesis and are believed to be derived from endosymbiotic cyanobacteria. In glaucophytes, perhaps
2655-515: The land plants or Embryophytes which emerged within them) and the glaucophytes , which together make up the oldest evolutionary lineages of photosynthetic eukaryotes, the Archaeplastida . A secondary endosymbiosis event involving an ancestral red alga and a heterotrophic eukaryote resulted in the evolution and diversification of several other photosynthetic lineages such as Cryptophyta , Haptophyta , Stramenopiles (or Heterokontophyta) , and Alveolata . In addition to multicellular brown algae, it
2714-420: The last common ancestor of Archaeplastida, which could explain how it obtained its chloroplasts, or if it is a trait regained by horizontal gene transfer . Since then more species of mixotrophic green algae, such as Pyramimonas tychotreta and Mantoniella antarctica , has been found. Evidence for primary endosymbiosis includes the presence of a double membrane around the chloroplasts; one membrane belonged to
2773-454: The living cell produces a layer of wall material that seals off the plug. The pit connections have been suggested to function as structural reinforcement, or as avenues for cell-to-cell communication and transport in red algae, however little data supports this hypothesis. The reproductive cycle of red algae may be triggered by factors such as day length. Red algae reproduce sexually as well as asexually. Asexual reproduction can occur through
2832-429: The most primitive members of the group, the chloroplast is called a cyanelle and shares several features with cyanobacteria, including a peptidoglycan cell wall, that are not retained in other members of the group. The resemblance of cyanelles to cyanobacteria supports the endosymbiotic theory . The cells of most archaeplastidans have walls, commonly but not always made of cellulose. The Archaeplastida vary widely in
2891-424: The name Plantae is ambiguous, since it has also been applied to less inclusive clades , such as Viridiplantae and embryophytes . To distinguish, the larger group is sometimes known as Plantae sensu lato ("plants in the broad sense"). To avoid ambiguity, other names have been proposed. Primoplantae, which appeared in 2004, seems to be the first new name suggested for this group. Another name applied to this node
2950-568: The oldest groups of eukaryotic algae . The Rhodophyta comprises one of the largest phyla of algae , containing over 7,000 recognized species within over 900 genera amidst ongoing taxonomic revisions. The majority of species (6,793) are Florideophyceae , and mostly consist of multicellular , marine algae, including many notable seaweeds . Red algae are abundant in marine habitats. Approximately 5% of red algae species occur in freshwater environments, with greater concentrations in warmer areas. Except for two coastal cave dwelling species in
3009-472: The oldest plant-like fossils ever found by about 400 million years. 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. Calcite crusts that have been interpreted as the remains of coralline red algae, date to
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#17328024718843068-530: The polysaccharides agarose and agaropectin that can be extracted from the cell walls as agar by boiling. The internal walls are mostly cellulose. They also have the most gene-rich plastid genomes known. Red algae do not have flagella and centrioles during their entire life cycle. The distinguishing characters of red algal cell structure include the presence of normal spindle fibres, microtubules, un-stacked photosynthetic membranes, phycobilin pigment granules, pit connection between cells, filamentous genera, and
3127-419: The production of spores and by vegetative means (fragmentation, cell division or propagules production). Red algae lack motile sperm . Hence, they rely on water currents to transport their gametes to the female organs – although their sperm are capable of "gliding" to a carpogonium 's trichogyne . Animals also help with the dispersal and fertilization of the gametes. The first species discovered to do so
3186-585: The red algae using molecular and traditional alpha taxonomic data; however, the taxonomy of the red algae is still in a state of flux (with classification above the level of order having received little scientific attention for most of the 20th century). A major research initiative to reconstruct the Red Algal Tree of Life (RedToL) using phylogenetic and genomic approach is funded by the National Science Foundation as part of
3245-402: The red/green algae and other lineages. This study provides insight on how rich mesophilic red algal gene data are crucial for testing controversial issues in eukaryote evolution and for understanding the complex patterns of gene inheritance in protists. The name Archaeplastida was proposed in 2005 by a large international group of authors (Adl et al. ), who aimed to produce a classification for
3304-451: The reduction reached 77%. The World Bank predicted the industry could be worth ~$ 1.1 billion by 2030. As of 2024, preparation included three stages of cultivation and drying. Australia's first commercial harvest was in 2022. Agriculture accounts for 37% of the world’s anthropogenic methane emissions. One cow produces between 154 to 264 pounds of methane/yr. Archaeplastida The Archaeplastida (or kingdom Plantae sensu lato "in
3363-525: Was formerly attributed to the presence of pigments (such as phycoerythrin ) that would permit red algae to inhabit greater depths than other macroalgae by chromatic adaption, recent evidence calls this into question (e.g. the discovery of green algae at great depth in the Bahamas). Some marine species are found on sandy shores, while most others can be found attached to rocky substrata. Freshwater species account for 5% of red algal diversity, but they also have
3422-534: Was made on the basis of the analysis of the plastid genomes. Over 7,000 species are currently described for the red algae, but the taxonomy is in constant flux with new species described each year. The vast majority of these are marine with about 200 that live only in fresh water . Some examples of species and genera of red algae are: Red algal morphology is diverse ranging from unicellular forms to complex parenchymatous and non- parenchymatous thallus. Red algae have double cell walls . The outer layers contain
3481-502: Was proposed. The placing of algal groups is supported by phylogenies based on genomes from the Mesostigmatophyceae and Chlorokybophyceae that have since been sequenced. Both the "chlorophyte algae" and the "streptophyte algae" are treated as paraphyletic (vertical bars beside phylogenetic tree diagram) in this analysis. The classification of Bryophyta is supported both by Puttick et al. 2018, and by phylogenies involving
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