Soft corals

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Soft corals
Sapling soft coral

Sapling soft coral

Systematics
without rank: Tissue animals (Eumetazoa)
Trunk : Cnidarians (Cnidaria)
Class : Flower animals (anthozoa)
Subclass : Octocorallia
Order : Soft corals
Scientific name
Alcyonacea
Lamouroux , 1816

The soft corals (Alcyonacea) are an order of the Octocorallia within the flower animals (Anthozoa). They are animal colonies that consist of many individual polyps .

features

They grow branched, tree-shaped, lobed, crusty or finger-shaped. Like all animals from the lower class (Octocorallia), the single polyp has 8 feathered tentacles, and the stomach space is divided into 8 chambers by 8 longitudinal walls (mesenteries). In many species the colonies also have regressed tubular polyps (siphonozoids) whose task is to pump or drain water into the body of the colony. This allows the soft corals to stretch and stabilize.

In contrast to the hard corals (Scleractinia) from the subclass Hexacorallia , soft corals do not have a solid calcareous skeleton, but mostly have small calcified needles ( sclerites ) in their bodies as strengthening elements .

The species living in sunny shallow water live in a symbiosis with single-celled, symbiotic algae ( zooxanthellae ).

Soft corals are predominantly brown, yellow or green in color. The species that live in deeper regions or in the shade under rocky overhangs are also often bright red, orange or purple in color.

distribution

The soft corals are found in all seas worldwide, but most species live in the warm, tropical seas in shallow water. But even in the deep sea and the Antarctic Ocean there are some species. The Dead Sea Hand is the only coral in the North Sea.

Systematics

The soft corals, which belong to the eight-pointed flower animals, are only distantly related to the reef-forming stony corals (Scleractinia). The system of soft corals is very unclear. The lack of fossils and the variability of growth forms make it impossible to understand the actual evolution of soft corals so far .

Leather corals (Alcyoniidae)

In 2006 a group led by the Australian soft coral taxonomist Philip Alderslade investigated the relationship of 103 genera of the Octocorallia with the help of mitochondal DNA . The analysis concerned 28 families of soft corals, sea ​​feathers (Pennatulacea) and the blue coral ( Heliopora coerulea ) and came to the conclusion that the Alcyoniina are not a monophyletic taxon . Instead, they form a large clade with the Holaxonia and some smaller groups. The Calcaxonia, together with the sea feathers and the blue coral, form the second. A third consists of smaller, lesser-known groups. Soft coral sub-taxa such as Scleraxonia , Stolonifera and many families are polyphyletic and are divided among the new clades. A revision of the Alcyonaria is necessary.

Aquarium keeping

Many types of soft corals can be kept in marine aquariums and are easier to keep for beginners than hard corals .

literature

  • Marymegan Daly, Mercer R. Brugler, Paulyn Cartwright, Allen G. Collin, Michael N. Dawson, Daphne G. Fautin, Scott C. France, Catherine S. McFadden, Dennis M. Opresko, Estefania Rodriguez, Sandra L. Romano & Joel L. Stake: The phylum Cnidaria: A review of phylogenetic patterns and diversity 300 years after Linnaeus. Zootaxa, 1668: 127-182, Wellington 2007 ISSN  1175-5326 Abstract - PDF
  • Catherine S. McFadden, Scott C. France et al. a .: A molecular phylogenetic analysis of the Octocorallia (Cnidaria: Anthozoa) based on mitochondrial protein-coding sequences. In: Molecular Phylogenetics and Evolution. 41, 2006, p. 513, doi : 10.1016 / j.ympev.2006.06.010 .
  • Katharina Fabricius, Philip Alderslade : Soft Corals and Sea Fans . 2001, Australian Institute of Marine Science. ISBN 0-642-32210-4
  • Yossi Loya and Ramy Klein: Die Welt der Korallen , Jahr Verlag Hamburg, 1998, ISBN 3-86132-226-9
  • Julian Sprung: Korallen , Dähne Verlag, 2000, ISBN 3-921684-87-0
  • Svein A. Fossa, Alf Jacob Nilsen: Korallenriff-Aquarium , Volume 4, Schmettkamp Verlag, 1995, ISBN 3-928819-05-4
  • Hans A. Baensch , Robert A. Patzner: Mergus Sea Water Atlas Volumes 2, 4 + 5, Mergus-Verlag, Melle
  • Rainer Kaiser: Lower animals of tropical and cold seas in the aquarium . Ulmer, Stuttgart 1991, ISBN 3-8001-7222-4
  • Matthias Bergbauer: Soft corals (Alcyonaria) - Selected ecological aspects , in the 5th International Seawater Symposium
  • KORALLE, marine aquarium specialist magazine, No. 12 December 2001 / January 2002, Natur und Tier Verlag Münster, ISSN  1439-779X
  • Harry Erhardt, Daniel Knop: Coral guide Indo-Pacific . 2005, Kosmos-Verlag, Stuttgart. ISBN 3-440-10293-9

Web links

Commons : Soft Coral (Alcyonacea)  - Collection of images, videos and audio files

Individual evidence

  1. ^ Catherine S. McFadden, Scott C. France et al. a .: A molecular phylogenetic analysis of the Octocorallia (Cnidaria: Anthozoa) based on mitochondrial protein-coding sequences. In: Molecular Phylogenetics and Evolution. 41, 2006, p. 513, doi : 10.1016 / j.ympev.2006.06.010 .