Sea feathers

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Sea feathers
Virgularia sp.

Virgularia sp.

Systematics
without rank: Tissue animals (Eumetazoa)
Trunk : Cnidarians (Cnidaria)
Class : Flower animals (anthozoa)
Subclass : Octocorallia
Order : Sea feathers
Scientific name
Pennatulacea
Verrill , 1865

The sea ​​feathers (Pennatulacea) are an order of the flower animals (Anthozoa), which colonize the sandy and silt soils in all oceans. They usually live at greater depths, only in the tropics also in shallow water. Around 440 species are currently described, but only about half of them are valid.

features

The strictly symmetrical polyp colony is very tough and strong. Its shape is reminiscent of a feather . From a central trunk that stands on a slightly swellable grave foot , numerous side branches branch off in the upper part in one level, on which the individual polyps stand. The strength of the colony is based on the deposition of horny substance ( pennatulin ) and calcareous needles , which are flat (on the foot) or needle-shaped (on the trunk). The polyps are very inconspicuous due to their small size (around 1 mm) and lack of color. The color of the coral skeleton is mostly bright purple-red, but much lighter inside. A colony reaches a height of 40 cm.

Sea feathers belong to the eight-pointed flower animals ( Octocorallia ). Your polyps always have eight feathered tentacles . They differ from all other flowering animals in that they have a primary or axial polyp, which consists of two parts: a foot, which is buried in the sand or mud floor, and a part protruding into the open water, from which the other polyps branch off . In the event of irritation, they can completely withdraw into their feet. The animals are bilaterally symmetrical and mostly feather-shaped. They are filter feeders and feed on the smallest of plankton . Some species can emit biologically produced light ( bioluminescence ).

The group of sea feathers represents an extraordinarily highly developed level of organization within the flower animals. The polyps are connected to one another by a very simple nervous system and therefore react to external influences like a single animal. Similar to the Dead Sea Hand , phases of polyp contraction alternate with those of expansion. The colonies often glow in the dark, attracting plankton organisms, which they catch and devour with their tiny tentacle heads. The colonies are sexually separated and the sex products are released into the open water, where fertilization then takes place. A planular larva forms from the fertilized egg , which changes to soil life and grows into a primary polyp. A whole colony emerges from this single animal through budding. So far, asexual reproduction is only known in the species Pennatula prolifera . In this species, the upper part of the stick constricts and forms a new colony.

distribution

Round sea feather (s) - Veretillum cynomorium

Cosmopolitan , on the European coasts in the Atlantic , English Channel , North and Western Baltic Sea , Mediterranean .

habitat

The habitat of sea feathers is clay, sand and soft soils at a depth of 20 to 2000 meters.

Systematics

The sea feathers are traditionally seen as one of the three orders of the Octocorallia. A more recent phylogenetic investigation rejects the previous assumptions about the relationships and sees the sea feathers as close relatives of a gorgonian group ( Ellisellidae ). The sea feathers are monophyletic and together with their sister group, the gorgonian family Ellisellidae, form a previously unnamed taxon that is in a sister relationship to the blue coral ( Heliopora coerulea ). The unnamed taxon formed from these three taxa is compared to all gorgonians of the suborder Calcaxonia with the exception of the Ellisellidae. Together they all form a provisional Calcaxonia Pennatulacea clade , which is the second most species-rich clade of Octocorallia.

The traditional structure is as follows:

Fossil record

Sea feathers are often associated with representatives of the Ediacara fauna , such as Charnia . However, Jonathan B. Antcliffe and Martin D. Brasier categorically reject this connection. Evidence from the Cambrian Burgess slate is also doubtful. Reliable evidence comes from the Lower Cretaceous and the Palaeogene . The cross-section of the calcified axis is very similar to that of the Belemnites from Jurassic and Chalk . Confusion with fossil sea feathers was one reason for the alleged evidence of belemnites in the " Tertiary " (Palaeogene and Neogene ). Conversely, a supposed remnant of a sea feather from the Upper Triassic turned out to be the remainder of a belemnoid cephalopod.

swell

Individual evidence

  1. ^ Gary C. Williams: Living genera of sea pens (Goelenterata: Octocorallia: Pennatulacea): illustrated key and synopses. Zoological Journal of the Linnean Society, 113 (2): 93-140, London 2008 doi: 10.1111 / j.1096-3642.1995.tb00929.x
  2. ↑ CS McFadden, SC France, JA Sánchez, P. Alderslade: A molecular phylogenetic analysis of the Octocorallia (Cnidaria: Anthozoa) based on mitochondrial protein-coding sequences. ScienceDirect
  3. ↑ Systematic list of valid octocoral genera compiled by Gary C. Williams and Stephen D. Cairns ( Memento of the original from March 27, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (accessed December 8, 2009) @1@ 2Template: Webachiv / IABot / research.calacademy.org
  4. ↑ Georg August Goldfuß: Handbook of Zoology. First division. Nürnberg, Johann Leonhard Schrag, 1820 Online at archive.org (p. 90)
  5. ↑ Jonathan B. Antcliffe and Martin D. Brasier: Charnia and sea pens are poles apart. Journal of the Geological Society, 164 (1): 49-51, London 2007 doi: 10.1144 / 0016-76492006-080
  6. ↑ Michael J. Benton (Ed.): The Fossil Record 2. Chapman & Hall, London a. a., 1993 ISBN 0-412-39380-8
  7. ↑ [1]

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. In: Zootaxa. 1668, Wellington 2007, pp. 127-182, ISSN  1175-5326 Abstract - PDF
  • Bernhard Werner: Cnidaria tribe. In: Hans-Eckard Gruner (Hrsg.): Textbook of Special Zoology. Volume I: Invertebrates Part 2: Cnidaria, Ctenophora, Mesozoa, Plathelminthes, Nemertini, Entoprocta, Nemathelminthes, Priapulida. 4th, completely revised edition. Gustav Fischer Verlag, Stuttgart 1984, ISBN 3-437-20261-8 , pp. 11-305.
  • H.-E. Gruner, H.-J. Hannemann, G. Hartwich, R. Kilias: Urania Tierreich, Invertebrates 1 (Protozoa to Echiurida). Urania-Verlag, ISBN 3-332-00501-4 .
  • Baensch, Patzner: Mergus Sea Water Atlas. Volumes 2, 4 + 5, Mergus-Verlag, Melle.

Web links

Commons : Sea Feathers  - Collection of images, videos and audio files