Ulvophyceae
| Ulvophyceae | ||||||||||||
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Sea lettuce ( ulva lactuca ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Ulvophyceae | ||||||||||||
| Mattox & KD Stewart |
The Ulvophyceae are a class of algae that belong to the group of Chlorophyta , one of the two large groups of green algae . Well-known representatives are the sea lettuce and the model organism Acetabularia .
features
The shapes of the Ulvophyceae range from unbegeißelten protozoa (coccal level of organization) over filamentous (trichal) to leaf-like scale thalli (example sea lettuce ), which are unbranched filaments most often. In addition to the usual multicellular forms with one nucleus per cell, there are those with multinucleated cells (siphonocladal) and sometimes macroscopic types with a large number of nuclei, but without cellular subdivision (siphonal, example Caulerpa ).
Flagellated stages have two or four flagella without mastigonema . The basal bodies have four microtubule roots in a cross shape and smaller roots in two sizes, alternating between two or more microtubules. The flagella are covered with scales and have a rhizoplast .
The cell wall contains polysaccharides and is more or less calcified. Plasmodesmata are absent. The cells divide by constriction with a closed, centric and persistent mitotic spindle. A phycoplast does not occur during cell division.
The life cycle is diplobionic, so there are free-living gametophytes and sporophytes . These two phases can be uniform (isomorphic) or different (heteromorphic). Other green algae groups mainly have a haplobiontic cycle.
Occurrence
The majority of the species live in sea water.
Systematics
The class may not be monophyletic . There are no clear synapomorphies . There are still insufficient genetic studies to clearly clarify the question. In 2004 there were five clearly differentiated groups, which are mostly classified as orders. Newer classification according to AlgaeBase (2017).
- Bryopsidales (including Caulerpales )
- Cladophorales (including Siphonocladales)
- Dasycladales
- Oltmannsiellopsidales
- Scotinosphaerales
- Trentepohliales
- Ulotrichales
- Ulvales
- Ulvophyceae incertae sedis
literature
- Sina M. Adl, Alastair GB Simpson, Mark A. Farmer, Robert A. Andersen, O. Roger Anderson, John A. Barta, Samual S. Bowser, Guy Bragerolle, Robert A. Fensome, Suzanne Fredericq, Timothy Y. James, Sergei Karpov, Paul Kugrens, John Krug, Christopher E. Lane, Louise A. Lewis, Jean Lodge, Denis H. Lynn, David G. Mann, Richard M. McCourt, Leonel Mendoza, Øjvind Moestrup, Sharon E. Mozley-Standridge, Thomas A. Nerad, Carol A. Shearer, Alexey V. Smirnov, Frederick W. Spiegel, Max FJR Taylor: The New Higher Level Classification of Eukaryotes with Emphasis on the Taxonomy of Protists. The Journal of Eukaryotic Microbiology 52 (5), 2005; Pages 399-451. doi : 10.1111 / j.1550-7408.2005.00053.x .
Web links
Individual evidence
- ^ Louise A. Lewis, Richard M. McCourt: Green Algae and the origin of land plants : American Journal of Botany 91 (10), 2004, pages 1535-1556. Abstract and full text
- ↑ http://www.algaebase.org/browse/taxonomy/?id=4357