Synurid
Encyclopedia
The synurids are a small group of heterokont
algae, found mostly in freshwater.
s, of which there are usually two, but sometimes only one divided into two lobes. The cells have two heterokont flagella
, inserted parallel to one another at the anterior, whose ultrastructure is a distinguishing characteristic of the group. Both asexual and isogamous sexual reproduction occur.
Both are common plankton
in lakes and ponds.
in 1987, who placed them in their own class Synurophyceae, based on an earlier suggestion by Cavalier-Smith
.
Chrysophyceae and Synurophyceae are part of a common clade.
Heterokont
The heterokonts or stramenopiles are a major line of eukaryotes currently containing more than 100,000 known species. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which are a primary component of plankton...
algae, found mostly in freshwater.
Characteristics
They are covered in silicate scales and spines. These are formed on the surface of the chloroplastChloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
s, of which there are usually two, but sometimes only one divided into two lobes. The cells have two heterokont flagella
Flagellum
A flagellum is a tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and plays the dual role of locomotion and sense organ, being sensitive to chemicals and temperatures outside the cell. There are some notable differences between prokaryotic and...
, inserted parallel to one another at the anterior, whose ultrastructure is a distinguishing characteristic of the group. Both asexual and isogamous sexual reproduction occur.
Genera
There are two major genera included here, divided into species mainly based on the structure of the scales.- Mallomonas are free-living individual cells, usually 50-100 μm in length. They have ornate scales and generally long spines.
- Synura occur as spherical colonies, with the cells oriented so that the flagella point outwards, each usually around 30 μm in length. The colonies are globular, rather than hollow, and spines are short if at all present.
Both are common plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
in lakes and ponds.
History
The synurids were originally included among the golden algae in the order Ochromonadales as the family Mallomonadaceae. They were formally defined as a separate group by AndersenAndersen
Andersen is a Danish-Norwegian patronymic surname meaning "son of Anders"...
in 1987, who placed them in their own class Synurophyceae, based on an earlier suggestion by Cavalier-Smith
Thomas Cavalier-Smith
Professor Thomas Cavalier-Smith , FRS, FRSC, NERC Professorial Fellow, is a Professor of Evolutionary Biology in the Department of Zoology, at the University of Oxford...
.
Chrysophyceae and Synurophyceae are part of a common clade.