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 or Prasinophyta 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 refers to 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 refers to 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. It forms spherical colonies of up to 50,000 cells. 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.
The Volvocaceae are a family of unicellular or colonial biflagellates, including the typical genus Volvox. The family was named by Ehrenberg in 1834, and is known in older classifications as the Volvocidae. All species are colonial and inhabit freshwater environments.
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.
In biology, a biological life cycle is a series of changes in form that an organism undergoes, returning to the starting state. "The concept is closely related to those of the life history, development and ontogeny, but differs from them in stressing renewal." Transitions of form may involve growth, asexual reproduction, or sexual reproduction.
Ulothrix is a genus of green algae in the family Ulotrichaceae.
The Chlorellales are an order of green algae in the class Trebouxiophyceae.
Cladophorales are an order of green algae, in the class Ulvophyceae.
Ulotrichales is an order of green algae in the class Ulvophyceae.
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.
Eudorina is a paraphyletic genus in the volvocine green algae clade. Eudorina colonies consist of 16, 32 or 64 individual cells grouped together. Each individual cell contains flagella which allow the colony to move as a whole when the individual cells beat their flagella together. Description by GM Smith :
Pleodorina is a genus of colonial green algae in the family Volvocaceae. Description by Gilbert M. Smith.
Pleodorina Shaw 1894:
Colonies always motile; spherical to sub-spherical, with 32-128 cells lying some distance from one another just within the periphery of the homogeneous, hyaline, gelatinous, colonial envelope and not connected by cytoplasmic strands. Cells differentiated into those that are purely vegetative in character and those capable of dividing to form daughter colonies. All but four cells of the colony reproductive or about half reproductive and half vegetative. Cells spherical to ovoid in shape. Vegetative cells with a cup-shaped chloroplast containing one pyrenoid; a large anterior eyespot; two cilia of equal length with two contractile vacuoles at their base. Reproductive cells at first like the vegetative cells, later with a more massive chloroplast that eventually contains several pyrenoids. The eyespot and cilia of reproductive cells disappearing when they are mature.
Hemiflagellochloris is a monotypic genus of green algae in the family Volvocaceae. It has only one known species, Hemiflagellochloris kazakhstanica.
Platydorina is a genus of green algae in the family Volvocaceae.
Platymonas is a genus of green algae in the family Volvocaceae.
Volvulina is a genus of colonial green algae in the family Volvocaceae. The colony (coenobium) is broadly ellipsoidal or spherical and consists of a fixed number of cells, usually 16 in mature individuals. The cells are located at periphery of the coenobium and separated from each other by being embedded in a swollen sack. The cell body is lens-shaped or half spherical when mature with two flagella. The chloroplast is dish- or bowl-shaped. Pyrenoids may be present or absent, the stigma large. The nucleus is centrally located and there may be 4 to 8 contractile vacuoles. Sexual reproduction is by isogamy.
Goniaceae is a family of algae in the order Chlamydomonadales, that includes the genera Astrephomene and Gonium. Members of the Goniaceae are distinguished from those of the Volvocaceae by having each cell surrounded by a tripartite boundary of the extracellular matrix, as opposed to the entire colony being surrounded by the tripartite boundary in Volvocaceae.
Scenedesmus obliquus is a green algae species of the genus Scenedesmus.
