|
Search over 100 encyclopedias and dictionaries: |
Research categories | Follow us on Twitter |
Research categories
View all topics in the newsView all reference sources at Encyclopedia.com |
|||
Zoantharia
Zoantharia (zoantharian corals, Hexacorallia; class Anthozoa) Subclass of solitary and colonial anthozoans which are many tentacled and have an enteron (gastrovascular cavity) divided by numerous paired mesenteries. The basal tissues secrete a corallum (cup) made of aragonite, which has an outer epitheca (skin) and radially arranged septa (see SEPTUM). The mesenteries are placed between the septa. The first group appeared in the Ordovician and is divided into four orders: Rugosa; Scleractinia; Tabulata; and Heterocorallia. Scleractinian zoantharians (Mesozoic to Recent) are responsible at the present time for building coral reefs, restricted to tropical areas. They may build wave-resistant structures, sometimes very thick, and are usually associated with other organisms, e.g. calcareous algae. Organic build-ups also took place in the Palaeozoic, and although zoantharians were present they did not always represent the major part of the fauna. Stromatoporoids (Stromatoporoidea), algae, etc., are associated with zoantharians in these build-ups and it is not always certain whether Palaeozoic reefs were comparable with modern or Mesozoic examples. It is unlikely that Palaeozoic zoantharians were reef-frame builders in the sense that modern scleractinians are, and probable that organisms other than corals formed the wave-resistant structures.
|
|
|
Cite this article
AILSA ALLABY and MICHAEL ALLABY. "Zoantharia." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "Zoantharia." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O13-Zoantharia.html AILSA ALLABY and MICHAEL ALLABY. "Zoantharia." A Dictionary of Earth Sciences. 1999. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-Zoantharia.html |
|
Zoantharia
Zoantharia (Hexacorallia; phylum Cnidaria, class Anthozoa) A subclass of solitary and colonial anthozoans, with or without a calcareous exoskeleton, that are characterized by paired mesenteries being first developed in a cycle of six; and by the insertion of new pairs in two (ventrolateral), four (lateral and ventrolateral), or all six primary exocoels. Zoantharia first appeared in the Ordovician.
|
|
|
Cite this article
MICHAEL ALLABY. "Zoantharia." A Dictionary of Zoology. 1999. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Zoantharia." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O8-Zoantharia.html MICHAEL ALLABY. "Zoantharia." A Dictionary of Zoology. 1999. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-Zoantharia.html |
|
Hexacorallia
Hexacorallia Alternative name for the order Scleractinia (stony corals).
|
|
|
Cite this article
AILSA ALLABY and MICHAEL ALLABY. "Hexacorallia." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "Hexacorallia." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O13-Hexacorallia.html AILSA ALLABY and MICHAEL ALLABY. "Hexacorallia." A Dictionary of Earth Sciences. 1999. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-Hexacorallia.html |
|
Hexacorallia
Hexacorallia See ZOANTHARIA.
|
|
|
Cite this article
MICHAEL ALLABY. "Hexacorallia." A Dictionary of Zoology. 1999. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Hexacorallia." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O8-Hexacorallia.html MICHAEL ALLABY. "Hexacorallia." A Dictionary of Zoology. 1999. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-Hexacorallia.html |
|
Search over 100 encyclopedias and dictionaries:
HighBeam™ Research, Inc. © Copyright 2012. All rights reserved.
The Encyclopedia.com advertising network includes:
