Raphidophyceae

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Raphidophyceae
Goniostomum semen

Goniostomum semen

Systematics
Classification : Creature
Domain : Eukaryotes (eukaryota)
without rank: Diaphoreticks
without rank: Sar
without rank: Stramenopiles (stramenopiles)
without rank: Raphidophyceae
Scientific name
Raphidophyceae
Chadefaud , 1950, emend. Silva, 1980

The Raphidophyceae are a group of phototrophic , unicellular algae that move through flagella . From a phylogenetic point of view, they are placed next to the stramenopiles .

Way of life and characteristics

The representatives of the Raphidophyceae, sometimes also referred to as chloromonads, live mainly in freshwater plankton; they can be found in small ponds, ponds and also in moors. Some species are also found in salt water on the coast of the sea. They are sensitive to contamination, so the species Gonyostomum semen is a good bio-indicator for dystrophic waters (brown water lakes).

All species are single-celled heterocellularly flagellated with a drag scourge and a forward-directed traction scourge (locomotor scourge) . The flagellum, directed forward, has cilia, the rear is smooth. As single-cell organisms, they are relatively large, they can reach a size of up to 0.1 millimeters.

They do not have a solid cell wall , instead a reinforced pellicle surrounds the interior of the cell ( protoplasm ). Trichocysts lie under the pellicle , they are used for defense. In the case of algae, trichocysts are only found in the Dinophyta and similar forms in the Cryptophyta .

The plastids are green to yellow-green in color and contain chlorophyll a, c1 and c2. The main accessory pigments include β-carotene and the xanthophylls diadinoxanthin , diatoxanthin and vaucheriaxanthin . There are no pyrenoids present. As reserve substances are lipids used.

Reproduction

In the Raphidophyceae only asexual reproduction is known. They usually multiply by dividing the cell longitudinally in the active, swimming state. Some, for example species of the genus Vacuolaria , also multiply under a gelatinous layer. The daughter cells remain surrounded by this layer for some time until they separate from each other due to the dissolution of the jelly.

Examples

The genus Gonyostomum is found worldwide in peat swamps and dystrophic lakes. The species Gonyostomum semen can survive unfavorable living conditions in the form of cysts . Vacuolaria virescens is surrounded by a gelatinous layer during reproduction, on which bacteria can also accumulate. This species lives in small pools and in dystrophic ponds. Fibrocapsa japonica is one in 1973 in coastal to Japan discovered species, the neurotoxins can form. These poisons can be fatal to various fish. When this species begins to multiply rapidly and form an algal bloom , it will cause great economic damage to Japanese coastal fisheries. This species has also occurred more frequently on European coasts since the early 1990s. In 1995 it was also found in the German Wadden Sea. Some species in the marine genus Chattonella can also produce toxins that are dangerous to fish.

Systematics

The Raphidophyceae are also referred to, mostly in botany, as Chloromonadophyceae. The name is also spelled with an additional i : Raphid i ophyceae. Since they are single-celled organisms, these phototrophic organisms are also treated in zoology from a historical perspective. Here they are considered to be the order Chloromonadina of the heteroconta . The name Raphidomonadea is also common here.

According to the system used here, the following genera are known:

swell

  1. ↑ Dinabandhu Sahoo, Joseph Seckbach: The Algae World (Cellular Origin, Life in Extreme Habitats and Astrobiology) . Springer, 2015, ISBN 978-94-017-7320-1 .
  2. ↑ Khan S., Arakawa O. & Onoue Y. 1996: Neurotoxin production by a chloromonad Fibrocapsa japonica (Raphidophyceae) . J. World Aquacult. Soc. 27: page 254–263.
  3. ↑ Toriumi S. & Takano H. 1973: A new genus in the Chloromonadophyceae from Atsumi Bay , Japan. Bull. Tokai Reg. Fish. Res. Lab. 76: pages 25–35.
  4. ↑ BLMP (2000), Meeresumwelt 1994–1996 , volume 2. Federal Maritime and Hydrographic Agency (BSH), Hamburg and Rostock
  5. ^ S. Khan, O. Arakawa and, Y. Onoue (1996): A toxicological study of the marine phytoflagellate, Chattonella antiqua (Raphidophyceae). Phycologia: May 1996, Vol. 35, No. 3, pp. 239-244.
  6. ↑ Westheide, Wilfried; Rieger, Reinhard (Hrsg.): Special zoology. Part 1: Protozoa and invertebrates . 2nd edition. Spektrum Akademischer Verlag 2006. ISBN 3-8274-1575-6
  7. ↑ Adl et al., 2005: 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 .

literature

Web links

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