| Chlainomonas | |
|---|---|
 | |
| Chlainomonas sp. | |
Scientific classification  | |
| (unranked): | Viridiplantae |
| Division: | Chlorophyta |
| Class: | Chlorophyceae |
| Order: | Chlamydomonadales |
| Family: | Chlamydomonadaceae |
| Genus: | Chlainomonas Christen |
| Type species | |
| Chlainomonas ovalis H.R.Christen [1] | |
| Species | |
Chlainomonas is a genus of algae in the family Chlamydomonadaceae. [2] They are found in freshwater habitats or on snow, where they are one of the main algae responsible for causing watermelon snow. [3]
Chlainomonas consists of single, ovate cells with four apical flagella attached at the tip. The protoplast is separated from the cell wall by a thick, hyaline layer; it is often filled with red pigments. There is a single chloroplast filling the cell. Pyrenoids are absent, or may be otherwise difficult to observe within the cytoplasm. There are typically two contractile vacuoles at the apex of the cell. Some species have a stigma. [1]
Chlainomonas reproduces asexually; no sexual reproduction has been observed in this genus. [1] The mode of asexual reproduction in Chlainomonas is highly unusual. During Chlainomonas, new cells are produced when the protoplasm is squeezed through the cell envelope in a thin stream. This leads to the protoplast being divided into two halves, one of which is outside of the parent cell. [4] After this, the protoplast quickly becomes surrounded by a gelatinous layer, similar to the parent cell. [5]
When in snow, Chlainomonas is typically found as a resting spore [5] (also known as a cyst), [6] and may be in one of two different morphologies. In the first form, the spore is ellipsoidal and is covered with spines. In the second form, the resting spore forms a thick wall but no spines. Both are surrounded by an external envelope, with four grooves where the flagella would extend. [5]
Two species of Chlainomonas are commonly found in snow ( Chlainomonas kolii and C. rubra . [3] They have been reported from mountains in the Pacific Northwest and in New Zealand. [4] The third species, Chlainomonas ovalis , is a freshwater species. [4]
The genus Chlainomonas is monophyletic. However, it is embedded within a clade containing most of the species Chloromonas , rendering the latter genus paraphyletic. [7] It is most closely related to other snow-inhabiting species in the genus Chloromonas, but is not closely related to Chlamydomonas nivalis, a morphologically similar red snow alga. [4]
The Chlorophyceae are one of the classes of green algae, distinguished mainly on the basis of ultrastructural morphology. They are usually green due to the dominance of pigments chlorophyll a and chlorophyll b. The chloroplast may be discoid, plate-like, reticulate, cup-shaped, spiral- or ribbon-shaped in different species. Most of the members have one or more storage bodies called pyrenoids located in the chloroplast. Pyrenoids contain protein besides starch. Some green algae may store food in the form of oil droplets. They usually have a cell wall made up of an inner layer of cellulose and outer layer of pectose.
Chlorophyta is a taxon of green algae informally called chlorophytes. The name is used in two very different senses, so care is needed to determine the use by a particular author. In older classification systems, it is a highly paraphyletic group of all the green algae within the green plants (Viridiplantae) and thus includes about 7,000 species of mostly aquatic photosynthetic eukaryotic organisms. In newer classifications, it is the sister clade of the streptophytes/charophytes. The clade Streptophyta consists of the Charophyta in which the Embryophyta emerged. In this latter sense the Chlorophyta includes only about 4,300 species. About 90% of all known species live in freshwater. Like the land plants, green algae contain chlorophyll a and chlorophyll b and store food as starch in their plastids.
Volvox is a polyphyletic genus of chlorophyte green algae in the family Volvocaceae. Volvox species form spherical colonies of up to 50,000 cells, and for this reason they are sometimes called globe algae. They live in a variety of freshwater habitats, and were first reported by Antonie van Leeuwenhoek in 1700. Volvox diverged from unicellular ancestors approximately 200 million years ago.
Chlamydomonas is a genus of green algae consisting of about 150 species of unicellular flagellates, found in stagnant water and on damp soil, in freshwater, seawater, and even in snow as "snow algae". Chlamydomonas is used as a model organism for molecular biology, especially studies of flagellar motility and chloroplast dynamics, biogenesis, and genetics. One of the many striking features of Chlamydomonas is that it contains ion channels (channelrhodopsins) that are directly activated by light. Some regulatory systems of Chlamydomonas are more complex than their homologs in Gymnosperms, with evolutionarily related regulatory proteins being larger and containing additional domains.
Chlamydomonadales, also known as Volvocales, are an order of flagellated or pseudociliated green algae, specifically of the Chlorophyceae. Chlamydomonadales can form planar or spherical colonies. These vary from Gonium up to Volvox. Each cell has two flagella, and is similar in appearance to Chlamydomonas, with the flagella throughout the colony moving in coordination.
Chlamydomonas nivalis, also referred to as Chloromonas typhlos, is a unicellular red-coloured photosynthetic green alga that is found in the snowfields of the alps and polar regions all over the world. They are one of the main algae responsible for causing the phenomenon of watermelon snow, where patches of snow appear red or pink. The first account of microbial communities that form red snow was made by Aristotle. Researchers have been active in studying this organism for over 100 years.
In botany, a zoid or zoïd is a reproductive cell that possesses one or more flagella, and is capable of independent movement. Zoid can refer to either an asexually reproductive spore or a sexually reproductive gamete. In sexually reproductive gametes, zoids can be either male or female depending on the species. For example, some brown alga (Phaeophyceae) reproduce by producing multi-flagellated male and female gametes that recombine to form the diploid sporangia. Zoids are primarily found in some protists, diatoms, green alga, brown alga, non-vascular plants, and a few vascular plants. The most common classification group that produces zoids is the heterokonts or stramenopiles. These include green alga, brown alga, oomycetes, and some protists. The term is generally not used to describe motile, flagellated sperm found in animals. Zoid is also commonly confused for zooid which is a single organism that is part of a colonial animal.
Astrephomene is a genus of green algae in the family Goniaceae, order Chlamydomonadales. The genus was first described in 1937 by Pocock and named by Pockock in 1953.
Asteromonas is a genus of green algae in the family Asteromonadaceae. It has been described from saline, marine, and brackish environments. It is closely related to the genus Dunaliella, another species common in saline waters.
Brachiomonas is a genus of thalloid biflagellate green algae. These algae generally are found in marine or brackish waters, but can tolerate wide range of salinities. They may occur in freshwater pools near the sea and, occasionally, in polluted inland freshwater habitats.
Carteria is a genus of green algae in the family Chlamydomonadaceae. Carteria are similar in morphology to the common genus Chlamydomonas and differ by having four, rather than two, flagella at the vegetative stage.
Characiosiphon is a genus of green algae in the family Characiosiphonaceae. It contains a single species, Characiosiphon rivularis.
Lagerheimia is a genus of green algae in the family Oocystaceae. It is commonly found in freshwater habitats all over the world, although some species are rare and have only been recorded from Europe or the United States.
Neochloris is a genus of green algae in the family Neochloridaceae. It is found in freshwater aquatic and terrestrial soil habitats.
Planktosphaeria is a genus of green algae, specifically of the Chlorophyceae. It was first described by the phycologist Gilbert Morgan Smith in 1918, with Planktosphaeria gelatinosa as its type species. Species of Planktosphaeria are commonly found in freshwater plankton around the world.
Sorastrum is a genus of green algae in the family Hydrodictyaceae. It is a component of the phytoplankton of freshwater ponds, lakes, and ditches. Sorastrum is common in tropical to temperate regions of the world, but due to its small size it is often overlooked.
Stephanosphaera is a genus of green algae in the family Haematococcaceae, containing the single species Stephanosphaera pluvialis. It forms colonies of flagellated cells. Although it was once placed in the family Volvocaceae, it is not closely related to them; its sister is the unicellular genus Balticola.
Tetraspora is a genus of green algae in the family Tetrasporaceae of the order Chlamydomonadales, division Chlorophyta. Species of Tetraspora are unicellular green algae that exist in arrangements of four and consist of cells being packaged together in a gelatinous envelope that creates macroscopic colonies. These are primarily freshwater organisms, although there have been few cases where they have been found inhabiting marine environments and even contaminated water bodies. Tetraspora species can be found all around the globe, except in Antarctica. Despite the ubiquitous presence, the greatest growth of the genera's species is seen in the polar climatic zones.
Trebouxia is a unicellular green alga. It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and temperate regions. It can either exist in a symbiotic relationship with fungi in the form of lichen or it can survive independently as a free-living organism alone or in colonies. Trebouxia is the most common photobiont in extant lichens. It is a primary producer of marine, freshwater and terrestrial ecosystems. It uses carotenoids and chlorophyll a and b to harvest energy from the sun and provide nutrients to various animals and insects.
Treubaria is a genus of green algae, the sole genus in the family Treubariaceae. Treubaria is found in freshwater habitats and has a cosmopolitan distribution.