Selenastraceae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

green algae The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

in the order

Sphaeropleales Sphaeropleales is an order of green algae that used to be called Chlorococcales. The order includes some of the most common freshwater plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphe ...

. Members of this family are common components of the

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater Aquatic ecosystem, ecosystems. The name comes from the Greek language, Greek words (), meaning 'plant', and (), mea ...

in freshwater habitats worldwide. A few species have been found in brackish and marine habitats, such as in the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North European Plain, North and Central European Plain regions. It is the ...

Description

The family Selenastraceae includes solitary cells or colonies of cells. Cells are diverse in morphology; they may be coccoid to spindle-shaped in shape, with rounded or pointed ends. They may be sickle-shaped or spirally curved. Cells contain a

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 ...

with a

pyrenoid Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''An ...

. Except in the genus '' Chlorolobion'', the pyrenoid lacks a starch covering, making it difficult to observe using

light microscopy Microscopy is the technical field of using microscopes to view subjects too small to be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, el ...

. Cells range in size from 5 to 105 μm in length and 1.5 to 6.5 μm in width. Algae in this family reproduce asexually, exclusively by

autospore Autospores are a type of spores that are produced by algae to enable asexual reproduction and spread. They are non-motile and non-Flagellated cell, flagellated Aplanospore, aplanospores that are generated within a parent cell and have the same sha ...

s. A distinguishing characteristic of this family is the method of autospore formation: the

protoplast Protoplast (), is a biology, biological term coined by Johannes von Hanstein, Hanstein in 1880 to refer to the entire cell, excluding the cell wall. Protoplasts can be generated by stripping the cell wall from plant, bacterium, bacterial, or f ...

divides serially, with divisions being perpendicular to the longer axis of the cell. Once divided, the daughter cells realign to become parallel with the daughter cell, and are then released.

Taxonomy

Selenastraceae is

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

. Traditionally, genera and species have been defined based on morphological features, such as habit (solitary or colonial), cell shape, presence or absence of mucilage, and presence and absence of pyrenoids. However, both genera and species have been shown to be

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

. The genus '' Closteriopsis'' consists of narrow, sickle-shaped cells with one chloroplast and multiple pyrenoids. It has been placed in the Selenastraceae due to its morphological similarity to genera such as ''Monoraphidium'', but genetic analyses have shown that it is unrelated. It is currently placed in the family

Chlorellaceae Chlorellaceae are a family of green algae in the order Chlorellales. About 250 species are currently accepted in the family. Members of the family are distributed worldwide and are common in a variety of freshwater, terrestrial and marine enviro ...

Uses

Some varieties of Selenastraceae, mainly from ''Monoraphidium'' and ''Ankistrodesmus'', are promising candidates for

biodiesel Biodiesel is a renewable biofuel, a form of diesel fuel, derived from biological sources like vegetable oils, animal fats, or recycled greases, and consisting of long-chain fatty acid esters. It is typically made from fats. The roots of bi ...

production. These strains produce large amounts of lipids under optimal growth conditions. Some strains may also be suitable for cultivation in

wastewater Wastewater (or waste water) is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of do ...

, which would cut production costs.

References

{{Authority control Chlorophyceae families Sphaeropleales