The raphidophytes, formally known as Raphidomonadea
or Raphidophyceae (formerly referred to as Chloromonadophyceae and Chloromonadineae),
are a small group of
eukaryotic
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...
alga
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mi ...
e that includes both
marine
Marine is an adjective meaning of or pertaining to the sea or ocean.
Marine or marines may refer to:
Ocean
* Maritime (disambiguation)
* Marine art
* Marine biology
* Marine debris
* Marine habitats
* Marine life
* Marine pollution
Military
* ...
and
freshwater
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
.
All raphidophytes are
unicellular
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and ...
, with large cells (50 to 100
μm), but no
cell walls
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...
. Raphidophytes possess a pair of
flagella
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates.
A microorganism may have f ...
, organised such that both originate from the same
invagination
Invagination is the process of a surface folding in on itself to form a cavity, pouch or tube. In developmental biology, invagination is a mechanism that takes place during gastrulation. This mechanism or cell movement happens mostly in the vegetal ...
(or gullet). One flagellum points forwards, and is covered in hair-like
mastigonemes
Mastigonemes are lateral "hairs" that attach to protistan flagella. Flimsy hairs attach to the flagella of euglenid flagellates, while stiff hairs occur in stramenopile and cryptophyte protists.Hoek, C. van den, Mann, D. G. and Jahns, H. M. (1 ...
, while the other points backwards across the cell surface, lying within a
ventral
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...
groove. Raphidophytes contain numerous
ellipsoid
An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation.
An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...
chloroplast
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...
s, which contain
chlorophyll
Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...
s a, c
1 and c
2. They also make use of
accessory pigment Accessory pigments are light-absorbing compounds, found in photosynthetic organisms, that work in conjunction with chlorophyll ''a''. They include other forms of this pigment, such as chlorophyll ''b'' in green algal and higher plant antennae, wh ...
s including
β-carotene
β-Carotene is an organic, strongly coloured red-orange pigment abundant in fungi, plants, and fruits. It is a member of the carotenes, which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 ...
and
diadinoxanthin
Diadinoxanthin is a pigment found in phytoplankton. It has the formula C40H54O3. It gives rise to the xanthophylls diatoxanthin and dinoxanthin.
Diadinoxanthin is a plastid pigment. Plastid pigments include chlorophylls a and c, fucoxanthin, hete ...
. Unlike other heterokontophytes, raphidophytes do not possess the
photoreceptive organelle (or eyespot) typical of this group.
In terms of
ecology
Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...
, raphidophytes occur as
photosynthetic
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...
autotroph
An autotroph or primary producer is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) using carbon from simple substances such as carbon dioxide,Morris, J. et al. (2019). "Biology: How Life Works", ...
s across a range of
aquatic systems. Freshwater species are more common in
acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
ic waters, such as pools in
bog
A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; a ...
s. Marine species often produce large
blooms in summer, particularly in coastal waters. Off the Japanese coast, the resulting
red tide
A harmful algal bloom (HAB) (or excessive algae growth) is an algal bloom that causes negative impacts to other organisms by production of natural phycotoxin, algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are ...
s often cause disruption to
fish farms
upright=1.3, Salmon farming in the sea (mariculture) at Loch Ainort, Isle of Skye">mariculture.html" ;"title="Salmon farming in the sea (mariculture">Salmon farming in the sea (mariculture) at Loch Ainort, Isle of Skye, Scotland
Fish farming or ...
, although raphidophytes are not usually responsible for
toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
blooms.
The position of this group varied in former classifications. Some
protozoologist Protozoology is the study of protozoa, the "animal-like" (i.e., motile and heterotrophic) protists. The Protozoa are considered to be a subkingdom of Protista. They are free-living organisms that are found in almost every habitat. All humans have pr ...
s treated the chloromonads as an order within the
phytoflagellates. Some
phycologists classified them with the
Xanthophyceae
Yellow-green algae or the Xanthophyceae (xanthophytes) are an important group of heterokont algae. Most live in fresh water, but some are found in marine and soil habitats. They vary from single-celled flagellates to simple colonial and filamento ...
and the
Eustigmatophyceae
Eustigmatophytes are a small group (17 genera; ~107 species) of eukaryotic forms of algae that includes marine, freshwater and soil-living species.
All eustigmatophytes are unicellular, with coccoid cells and polysaccharide cell walls. Eus ...
in the division
Xanthophyta
Yellow-green algae or the Xanthophyceae (xanthophytes) are an important group of heterokont algae. Most live in fresh water, but some are found in marine and soil habitats. They vary from single-celled flagellates to simple colonial and filament ...
. Others considered them as related to the Chrysophyceae, Dinophyceae, or Cryptophyceae
Recently, the heliozoan
Actinophyrida was moved to the group.
Taxonomy
Classification based on Cavalier-Smith and Scoble 2013
* Class
Raphidomonadea
The raphidophytes, formally known as Raphidomonadea or Raphidophyceae (formerly referred to as Chloromonadophyceae and Chloromonadineae), are a small group of eukaryotic algae that includes both marine and freshwater species. All raphidophytes a ...
Silva 1980 emend. Cavalier-Smith 2013 Chadefaud 1950 emend. Silva 1980 s.l.">aphidophyceae Chadefaud 1950 emend. Silva 1980 s.l.**
nplaced genera*** Genus ''
Psammamonas''
Grant et al. 2013
*** Genus ''
Chloromorum''
Tomas et al.
** Subclass
Raphopoda Cavalier-Smith 2013
*** Order
Commatiida Cavalier-Smith 1997
**** Family
Commatiidae Cavalier-Smith 2013
***** Genus ''
Commation''
Thomsen & Larsen 1993
*** Order
Actinophyrida Hartmann 1913 Kühn 1926; Actinophrydea Hartmann 1913">ctinophrydia Kühn 1926; Actinophrydea Hartmann 1913**** Family
Actinosphaeriidae Cavalier-Smith 2013
***** Genus ''
Actinosphaerium
The actinophryids are an order of heliozoa, a polyphyletic array of stramenopiles, having a close relationship with pedinellids and ''Ciliophrys''. They are common in fresh water and occasionally found in marine and soil habitats. Actinophryids a ...
''
Ritter von Stein 1857 'Camptonema''_
Schaudinn_1894;_''Echinosphaerium.html" ;"title="Camptonema.html" ;"title="'Camptonema">'Camptonema''
Schaudinn 1894; ''Echinosphaerium">Camptonema.html" ;"title="'Camptonema">'Camptonema''
Schaudinn 1894; ''Echinosphaerium''
Hovasse 1965]
**** Family Helioraphidae
Cavalier-Smith 2013
***** Genus ''Heliorapha''
Cavalier-Smith 2013
**** Family Actinophryidae
Dujardin 1841
***** Genus ''
Actinophrys
The actinophryids are an order of heliozoa, a polyphyletic array of stramenopiles, having a close relationship with pedinellids and ''Ciliophrys''. They are common in fresh water and occasionally found in marine and soil habitats. Actinophryids a ...
''
Ehrenberg 1830 'Trichoda''_
Müller_1773_nomen_oblitum;_''Peritricha_(genus).html" ;"title="Trichoda.html" ;"title="'Trichoda">'Trichoda''
Müller 1773 nomen oblitum; ''Peritricha (genus)">Peritricha''
Bory de St.Vincent 1824 nomen dubium non Stein 1859]
** Subclass Raphidophycidae
Cavalier-Smith 2013 [Raphidophyceae
Chadefaud 1950 emend. Silva 1980 s.s.; Chloromonadophyceae
Rothmaler 1951; Raphidophyta]
*** Order
Raphidomonadales Throndsen 1993; Chloromonadida; Chloromonadales; Raphidomonadida Heywood & Leedale 1983; Chloromonadina Klebs 1892">hattonellales Throndsen 1993; Chloromonadida; Chloromonadales; Raphidomonadida Heywood & Leedale 1983; Chloromonadina Klebs 1892**** Genus ''
Viridilobus''
Demir-Hilton et al. 2012
**** Family
Fibrocapsaceae Cavalier-Smith 2013
***** Genus ''
Fibrocapsa''
Toriumi & Takano 1973
**** Family
Haramonadaceae Cavalier-Smith 2013
***** Genus ''
Haramonas''
Horiguchi 1996
**** Family
Chattonellaceae Throndsen
***** Genus ''
Oltmannsia''
Schiller 1925
***** Genus ''
Chlorinimonas''
Yamaguchi et al. 2010
***** Genus ''
Heterosigma''
Hada 1967 ex Hara & Chihara 1987
***** Genus ''
Chattonella
''Chattonella'' is a genus of marine raphidophytes associated with red tides. A technique using monoclonal antibodies can be used to identify the genus, while the RAPD reaction can be used to distinguish between different species within the ge ...
''
Biecheler 1936 'Hornellia''_
Subrahmanyan_1954;_''Hemieutreptia.html" ;"title="Hornellia.html" ;"title="'Hornellia">'Hornellia''
Subrahmanyan 1954; ''Hemieutreptia">Hornellia.html" ;"title="'Hornellia">'Hornellia''
Subrahmanyan 1954; ''Hemieutreptia''
Hada 1974]
**** Family Vacuolariaceae
***** Genus ''Swirenkoiamonas''
Skvortzov 1968
***** Genus ''Vacuolaria''
Cienkowski 1870
***** Genus ''Merotricha''
Mereschkowsky 1877
***** Genus ''
Gonyostomum''
Diesing 1866
References
{{Taxonbar, from=Q134928
Ochrophyta