The raphidophytes, formally known as Raphidophycidae or Raphidophyceae (formerly referred to as Chloromonadophyceae and Chloromonadineae), are a small group of

eukaryotic The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

algae that includes both marine 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. The term excludes seawater and brackish water, but it does include non-salty mi ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

. All raphidophytes are unicellular, with large cells (50 to 100 μm), but no cell walls. Raphidophytes possess a pair of

flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

, organised such that both originate from the same invagination (or gullet). One flagellum points forwards, and is covered in hair-like mastigonemes, while the other points backwards across the cell surface, lying within a ventral groove. Raphidophytes contain numerous ellipsoid

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

s, which contain

chlorophyll Chlorophyll 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 allows plants to absorb energy ...

s a, c₁ and c₂. They also make use of accessory pigments including β-carotene and diadinoxanthin. Unlike other heterokontophytes, raphidophytes do not possess the photoreceptive organelle (or eyespot) typical of this group. In terms of

ecology Ecology () is the natural science of the relationships among living organisms and their Natural environment, environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosystem, and biosphere lev ...

, raphidophytes occur as

photosynthetic Photosynthesis ( ) is a Biological system, system of biological processes by which Photoautotrophism, photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical ener ...

autotroph An autotroph is an organism that can convert Abiotic component, abiotic sources of energy into energy stored in organic compounds, which can be used by Heterotroph, other organisms. Autotrophs produce complex organic compounds (such as carbohy ...

s across a range of aquatic systems. Freshwater species are more common in

acid An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...

ic waters, such as pools in bogs. Marine species often produce large blooms in summer, particularly in coastal waters. Off the Japanese coast, the resulting red tides often cause disruption to fish farms, although raphidophytes are not usually responsible for toxic blooms. The position of this group varied in former classifications. Some protozoologists 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 filamen ...

and the Eustigmatophyceae in the division Xanthophyta. Others considered them as related to the Chrysophyceae, Dinophyceae, or Cryptophyceae Currently, raphidophytes are regarded as an independent lineage of algae within the class Raphidomonadea, which also includes the

heliozoa Heliozoa, commonly known as sun-animalcules, are microbial eukaryotes (protists) with stiff arms (Pseudopodia#Morphology, axopodia) radiating from their spherical bodies, which are responsible for their common name. The axopodia are microtubule- ...

n group Actinophryida.

Taxonomy

The classification based on Cavalier-Smith and Scoble 2013 recognizes only one order, Chattonellales. * Subclass Raphidophycidae Cavalier-Smith 2013 aphidophyceae Chadefaud 1950 emend. Silva 1980 s.s.; Chloromonadophyceae Rothmaler 1951; Raphidophyta** Order Chattonellales Throndsen in Tomas, 1993 emend. Yamaguchi, Nakayama, Murakami & Inouye, 2010 acuolariales ; 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 Vacuolariaceae hattonellaceae ; Gonyostomaceae **** Genus '' Oltmannsia'' Schiller 1925 **** Genus '' Chlorinimonas'' Yamaguchi et al. 2010 **** Genus '' Heterosigma'' Hada 1967 ex Hara & Chihara 1987 **** Genus '' Chattonella'' Biecheler 1936 '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, from1=Q134928, from2=Q21400364 Ochrophyta