Zooxanthellae
Zooxanthellae are protists that can live as endosymbionts in a number of living things. The zooxanthellae are mostly dinoflagellates , but chrysomonads , cryptomonads or diatoms also occur. The hosts are rhizaria (chamberlings alias foraminifera and radiolucent animals alias radiolaria ), stony corals (Scleractinia), many octocorallia , other flower animals (anthozoa), fire corals ( Millepora ), giant clams (Tridacnidae), but also some types of jellyfish . Also nudibranchs (Nudibranchia, z. B. Pteraeolidia ianthina ) and sponges sometimes have zooxanthellae. All corals that are involved in the construction of tropical coral reefs have zooxanthellae as endosymbionts.
![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/64/Giant_clam_zooxanthellae.jpg/220px-Giant_clam_zooxanthellae.jpg)
The zooxanthellae live in the host's body and supply it with sugar , starch and other organic products. Both the host and the protists benefit from the symbiosis , so it is a matter of mutualism. In the foraminifera , the symbiosis is optional, that is, both creatures in principle thrive without each other. The reef-forming hard corals of tropical coral reefs, on the other hand, die when they expel their zooxanthellae under stress, a phenomenon known as coral bleaching .
![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/5f/Zooxanthella.png/400px-Zooxanthella.png)
If it is not the protist cells as a whole but only the chloroplasts that are preserved, this is called kleptoplasty .
Individual evidence
- ↑ The radiolarians are probably polyphyletic and are composed of the taxa Polycystinea , Acantharia and Sticholonchia , which, like the Foraminifera, all belong to the Rhizaria; see Radiolaria .
- ^ Klaus Hausmann, Norbert Hülsmann, Renate Radek: Protistology . 3. Edition. Schweizerbart, 2003, ISBN 3-510-65208-8 , pp. 341 .
- ↑ Bill Rudman: Zooxanthellae in nudibranchs on seaslugforum.net.
- ↑ S. Mariani, M.-J. Uriz, X. Turon: Larval Bloom of the oviparous sponge Cliona viridis : Coupling of larval abundance and adult distribution . In: Marine Biology (2000) 137: pp. 783-790
- ^ Peter Sitte , Elmar Weiler , Joachim W. Kadereit , Andreas Bresinsky , Christian Körner : Textbook of botany for universities . Founded by Eduard Strasburger . 35th edition. Spektrum Akademischer Verlag, Heidelberg 2002, ISBN 3-8274-1010-X , p. 704 .
- ↑ Klaus Nuglisch: Foraminiferen - marine Mikroorganismen , Wittenberg, A. Ziemsen Verlag 1985, ISBN 3740301155 , p. 25.
- ↑ Helmut Schuhmacher, Karen Loch, Wolfgang Loch, Wolf R. See: The bleaching of the corals . In: Biology in our time 3/2005: pp. 186–191, doi: 10.1002 / biuz.200410281
- ↑ Lithocircus on: Taxonomicon
Web links
- Wilfried Probst: Early evolution and symbiosis , European University of Flensburg, Institute of Biology and General Studies and Didactics: §Pflanzentiere and Kleptoplasten , accessed on April 19, 2019