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Topic: Cnidaria


  
  Cnidaria   (Site not responding. Last check: 2007-10-25)
The exclusively aquatic phylum Cnidaria is represented by polyps such as sea anemones and corals, and by medusae such as jellyfish.
Cnidaria is thought to have one of the longest fossil histories of metazoan phlya with representatives in the Ediacaran fauna of the late Precambrian (Scrutton 1979).
Cnidaria, therefore, is a well circumscribed taxon; it is considered by many to be a sister group of all metazoans other than sponges.
tolweb.org /tree?group=Cnidaria&contgroup=Animals   (2407 words)

  
  Cnidaria - HighBeam Encyclopedia   (Site not responding. Last check: 2007-10-25)
Cnidaria or Coelenterata, phylum of invertebrate animals comprising the sea anemones, corals, jellyfish, and hydroids.
Systematics and Biogeography of the Jellyfish Aurelia labiata (Cnidaria: Scyphozoa).
Identification of synaptophysin-like immunoreactivity in the sea anemone Condylactis gigantea (Cnidaria: Anthozoa).
www.encyclopedia.com /doc/1E1-cnidaria.html   (1264 words)

  
 Cnidaria Summary
New research indicates that cnidaria seem to possess a mesoderm in addition to the ecto- and endoderm, from which the musculature of the medusa develops, among others.
Cnidaria have great ecological significance through one of their subgroupings, the skeletal coral, which form coral reefs in shallow waters.
Our understanding of fossil groups is varied; while those cnidaria that were formed of soft tissue only remain today in very exceptional cases, the fossil record of, for example, corals is very well known due to the lime remains they left behind.
www.bookrags.com /Cnidaria   (3570 words)

  
 Cnidaria - Wikipedia, the free encyclopedia
Concentrations of nerve cells are found in the mouth area of polyps (the hypostome), on the tentacles and stem (pedunculus), and with jellies a ring of nerves is often found around the screen.
Asexual reproduction via budding is common among cnidaria, particularly among the Hydrozoa class.
As mentioned in the introduction, cnidaria were classically grouped together with ctenophora as Coelenterata.
en.wikipedia.org /wiki/Cnidaria   (2661 words)

  
 Cnidaria - Anemones
Members of the Phylum Cnidaria include the Anemones and are grouped with the soft and hard corals and the hydroids.
For some Cnidaria forms, the juveniles may remain in the coelenteron and be brooded there, such as in the Waratah Anemone, Actinia tenebrosa.
In Cnidaria there are groups that are primarily medusoid in life style, with only a brief, insignificant polyp stage, and others that are primarily polyps, with only a brief medusoid life-stage.
www.mesa.edu.au /friends/seashores/cnidaria.html   (407 words)

  
 Highbeam Encyclopedia - Search Results for Cnidaria
sea whip erect colony of marine animals of the phylum Cnidaria, with whiplike branches.
Some animals of this group are always polyps, some are always medusae, and some exhibit both a polyp and a medusa stage in their life cycle.
Homeoboxes in sea anemones (Cnidaria; Anthozoa): a PCR-based survey of Nematostella vectensis and Metridium senile.
www.encyclopedia.com /SearchResults.aspx?Q=Cnidaria   (608 words)

  
 Cnidaria (jellyfish, sea anemones, corals and their relatives)
Cnidaria have a body wall that is made up of only two layers of cells, like that of sponges; other "true" animals (eumetazoa) have three.
Prescott considers the nervous system found in cnidaria to be a fundamental advance in the evolution of what he calls "action selection" or the problem of "resolving conflicts between competing behavioural alternatives" (2001, p.
Unlike bacteria, cnidaria are multicellular creatures, which face the task of co-ordinating their entire bodies in response to sudden changes in their environment.
www.angelfire.com /linux/vjtorley/cnidaria.html   (2059 words)

  
 Palaeos Invertebrates: Cnidaria: Cnidaria
Sea anemones and corals are typical of the polyp form, while jellyfish are typical medusae When you look at it, you can see that these are the same body form, except that one is upside down, while the other is not.
Nematocysts are to cnidaria what choanocysts are to sponges.
Systema Naturae 2000 / Classification - Phylum Cnidaria
www.palaeos.com /Invertebrates/Cnidaria/Cnidaria.htm   (749 words)

  
 Cnidaria
Cnidaria, phylum of multicellular, radially symmetrical INVERTEBRATES (eg, hydroids, JELLYFISH, sea anemones, CORALS) dating to late Precambrian era (630-570 million years ago).
Cnidaria [Gk knide, "nettle";] are characterized by their unusual stinging cells.
Anemones and corals perceive stimuli by sensory cells scattered throughout the epidermis.
www.thecanadianencyclopedia.com /PrinterFriendly.cfm?ArticleId=A0001701   (954 words)

  
 The Anemones, Corals and Jellyfish (Phylum Cnidaria)
The name Cnidaria has now pretty much replaced the older term of Coelenterata (pronounced selenterata) which these days is often applied to both the Cnidaria and the Ctenophora together, these two phyla are also known as the Radiate Animals because they both have radial or biradial symmetry.
All the Cnidaria are aquatic and nearly all are marine.
Generally speaking Polyps are tube shaped and sedentary with a ring of tentacles around the mouth, Medusae are umbrella or bell shaped, free living and have a central projection on the inside of the umbrella which supports the mouth and their tentacles around the rim of the umbrella.
www.earthlife.net /inverts/cnidaria.html   (1212 words)

  
 Systematics of Cnidaria   (Site not responding. Last check: 2007-10-25)
However, a recent cladistic analysis (Schuchert, 1993) and avaliable molecular data suggest that the Anthozoa, the only group of living cnidarians that completely lacks a medusoid "jellyfish" stage in the life cycle, are in fact most primitive.
The phylum Ctenophora, which includes the "comb jellies," "sea gooseberries," and "Venus's girdles," is not currently considered to be part of the Cnidaria; however, the two are close relatives.
The Cnidaria and Ctenophora are grouped together by some workers as the Coelenterata.
www.ucmp.berkeley.edu /cnidaria/cnidariasy.html   (165 words)

  
 Nearctica - Natural History - Cnidaria and Ctenophora   (Site not responding. Last check: 2007-10-25)
The Cnidaria (sometimes called the Coelenterata) are comprised of a variety of aquatic organisms including the corals, sea anemones, jellyfish, corals, and sea fans.
Although the Cnidaria have a basically simple, radially symmetric body plan despite superficial differences in the animals, there is more cell specialization than in the sponges.
Morphology and systematic relationships among the Cnidaria with a phylogenetic tree.
www.nearctica.com /nathist/miscanim/cnidaria.htm   (790 words)

  
 [No title]
Closely related to the phylum Cnidaria is the phylum Ctenophora containing organisms called "comb jellies." Both cnidarians and ctenophores are considered to be at the "tissue grade" of body construction.
PHYLUM CNIDARIA Cnidarians are radially symmetrical organisms that have one of two basic body forms: the polyp form or the medusa form.
The phylum Cnidaria is divided into three classes based on characteristics such as life cycle, the morphology of the GV cavity, and the presence or absence of cells in the mesoglea.
www.brown.edu /Courses/Bio_41/labcnidaria.doc   (4494 words)

  
 BIO 5 PLANT BIOLOGY
However, unlike the sponges in which the cells are independent of one another, the cells of animals in the Cnidaria are organized into tissues.
The animals in the Phylum Cnidaria have radial symmetry.
This means that, while the animal has a digestive cavity that allows it to ingest relatively large prey, there is only one opening to the gvc.
www.csus.edu /indiv/r/reihmanm/cnidaria.htm   (970 words)

  
 Cnidaria — FactMonster.com
Cnidaria: Class Anthozoa - Class Anthozoa Class Anthozoa includes Cnidaria that have no jellyfish stage.
Cnidaria: Class Scyphozoa - Class Scyphozoa Cnidarians of class Scyphozoa have a predominant jellyfish stage.
Cnidaria: Class Hydrozoa - Class Hydrozoa The Hydrozoa include solitary or colonial cnidarians, which have a noncellular...
www.factmonster.com /ce6/sci/A0812660.html   (353 words)

  
 Cnidaria (bluebottles, jellyfish, corals, sea anemones)
Cnidaria come in two main forms: polyps, that usually stays in one place (e.g.
Bluebottles and their relatives (Siphonophora) are unusual in that each of them is basically a colony of floating polyps, one of which is inflated to form the float.
Some of the most important members of the Cnidaria are the corals that, in association with symbiotic algae, are able to lay down calcium carbonate and in this way build whole islands that people now live on.
www.museums.org.za /bio/cnidaria/index.htm   (227 words)

  
 Oceanlink | marine sciences education and fun
It is in the phylum Cnidaria, and has stinging cells which are characteristic of this group of animals.
The Phylum Cnidaria also includes the sea anemones and corals; all of these organisms possess stinging cells which are called cnidocytes.
Also, corals (which are animals in the Phylum Cnidaria, which means they are closely related to jellyfish and anemones)require high salinity waters (32-42 ppt), high light levels and relatively calm waters.
www.oceanlink.island.net /ask/cnidaria.html   (9979 words)

  
 Olympus MIC-D: Darkfield Gallery - Ancient Cnidaria Fossil
The phylum Coelenterata, also known as Cnidaria, includes the marine corals, sea fans, sea pens, sea anemones, hydras, and jellyfish.
Specialized stinging cells known as nematocysts or cnidae (thus, the alternative phylum name) are used to capture, hold, and reel in prey, as well as to assist in locomotion and defense.
Capable of either asexual or sexual reproduction, coelenterates are primitive invertebrates characterized by the radial symmetry typical of sessile, benthic filter feeders.
www.olympusmicro.com /micd/galleries/darkfield/cnideriahigh.html   (295 words)

  
 Cnidaria
The phylum cnidaria includes the jellyfish, anemones, corals and hydroids.
Their bodies can be visualized as being saclike, with only two cell layers - the outer "skin" or ectoderm and inner lining to the gut, the endoderm.
This association limits the reef corals to sunlit warm waters.
library.thinkquest.org /26153/marine/cnida.htm   (1506 words)

  
 [Cnidaria] Advice
I am a biochemist by training and have enjoyed learning about cnidaria despite a non-conventional route into the field.
I would expect that the next decade will involve further integration of disciplines, thus bringing field ecologists, behaviorists, molecular biologists, biochemists and cell biologists together to address the complex and remarkable research questions that arise during the study of cnidaria.
For this reason, I would recommend a training program that would allow for a broad base of academic and lab-based instruction and to avail yourself of 3 month lab rotations if the institution you choose has such.
maillists.uci.edu /mailman/public/cnidaria/2003-June/000589.html   (2145 words)

  
 cnidaria
There are four major groups of cnidarians: Anthozoa, which includes true corals, anemones, and sea pens; Cubozoa, the amazing box jellies with complex eyes and potent toxins; Hydrozoa, the most diverse group with siphonophores, hydroids, fire corals, and many medusae; and Scyphozoa, the true jellyfish.
The name Cnidaria comes from the Greek word "cnidos", which means stinging nettle.
As with the other cnidaria, hydra capture prey with nematocysts.
www.wm.edu /act2online/projects/fahey03/cnidaria.html   (707 words)

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