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Topic: Protostome


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 Protostome - Wikipedia, the free encyclopedia
Protostomes (from the Greek: first the mouth) are a taxon of animals.
The major distinctions between deuterostomes and protostomes are found in embryonic development.
Protostomes have what is known as spiral cleavage which is determinate, this meaning that the fate of the cells is determined as they are formed.
en.wikipedia.org /wiki/Protostome   (176 words)

  
 Protostomes from the Greek Greek first the mouth are a...   (Site not responding. Last check: 2007-11-07)
Protostomes have their early cell divisions diagonal to the polar axis forming a spiral arrangement of cells; this is called spiral cleavage spiral cleavage.
Protostomes have a determinate cleavage determinate cleavage: the fate of how each embryonic cell will turn out to be or function is typically fixed very early; the first four cells are separate and each will develop into a fixed quarter of the larva.
Protostomes are schizocoely schizocoely, where the mesoderm mesoderm splits and the split widens into a cavity that becomes the coelom coelom.
www.biodatabase.de /protostome   (274 words)

  
 Protostome237   (Site not responding. Last check: 2007-11-07)
In most protostomes cells simply fill in the interior of the gastrula to form the mesoderm, called schizocoelous development, but in deuterostomes it forms through evagination of the endoderm, called enterocoelic pouching.
The Ecdysozoa are protostomes, named after the common trait of growth by moulting or ecdysis.
The distinction between protostomes and deuterostomes is based on the direction in which the mouth (stoma) develops in relation to the blastopore.
population.en.infovx.com /en/protostome   (5132 words)

  
 Protostome Did You Mean protostome   (Site not responding. Last check: 2007-11-07)
The branch that was leading to protostome development must have continued to be deuterostomes a while after the split, until some remote ancestor evolved into the first protostome which gave rise to all the other present and extinct species and groups within this highly successful group.
The only surviving "non-protostomian" group from the ancient deuterostomian lineage that would eventually resulted in the protostomes would have been the ancestors of the Chaetognatha (arrow worms), which still has a deuterostomian development.
Evolving a different gastrulation and another way to turning the blastopore into a new individual, which is both backwards and upside down compared to how the blastopore evolved in their ancestors, would have been very difficult for the modern and advanced species of today to do.
www.did-you-mean.com /Protostome.html   (353 words)

  
 Protostome: Facts and details from Encyclopedia Topic   (Site not responding. Last check: 2007-11-07)
Protostomes (from the Greek A native or inhabitant of Greece
Ecdysozoa The ecdysozoa are a major group of protostome animals, including the arthropods (insects, arachnids, crustaceans and relatives), roundworms, and several smaller phyla....
Platyzoa The platyzoa are a group of protostome animals....
www.absoluteastronomy.com /p/protostome   (590 words)

  
 Bryozoan Introduction
Bryozoans, sometimes referred to as moss animals or ectoprocts are tiny, colonial organisms.
Their development does not follow either a true protostome or true deuterostome pattern.
They, along with the Phoronids (worm-like animals) and the Brachiopods (bivalve-like animals sometimes referred to as lampshells) are thus classified based on the presence of a specialized feeding structure called a lophophore, an extension of the body wall into a tentacled structure that surrounds the mouth and is either horseshoe-shaped or circular.
www.sms.si.edu /irlspec/IntroBryozoa.htm   (974 words)

  
 lesser-known protostome taxa: An introduction and a tribute to Robert P. Higgins, The Integrative and Comparative ...
The Lesser-Known Protostome Taxa: An Introduction and a Tribute to Robert P. Higgins1
This symposium was designed to play a role in renewing interest in the lesser-known animal groups, encourage their use in research and teaching and promote the relevance of high-level systematic studies.
The symposium was restricted to protostomes simply to narrow the scope so that it could be completed in a single day.
www.findarticles.com /p/articles/mi_qa4054/is_200206/ai_n9119413   (369 words)

  
 Kingdom   (Site not responding. Last check: 2007-11-07)
In today's lab we will examine two Phyla of Kingdom Animalia that are characterized by protostome development and are members of Lophotrochozoa.
The term protostome means "first mouth" which is a reference to the first opening of the digestive system.
Like Platyhelminthes, Rotifers are protostomes but they differ in having a body cavity.
bioweb.wku.edu /faculty/Lienesch/225/225lab3.html   (861 words)

  
 Protostome Condition   (Site not responding. Last check: 2007-11-07)
You chose the ancestor to the Annelida, Mollusca, and Arthropoda
The main structural evidence that the Mollusca, Annelida, and Arthropoda evolved from an ancestor that was not an ancestor to the other animals is that all three groups have all four main traits of protostomes.
The rest of the traits probably evolved in earlier ancestors, but are traditionally considered part of the protostome condition, so they are list ed here.
www.utm.edu /departments/cens/biology/rirwin/protostome.htm   (112 words)

  
 黃俊瑜 9/29   (Site not responding. Last check: 2007-11-07)
Here, we show that the complement of Hox genes in critical protostome phyla reflects these phylogenetic relationships and reveals the early evolution of developmental regulatory potential in bilaterians.
We have identified Hox genes that are shared by subsets of protostome phyla.
These include a diverged pair of posterior (Abdominal-B-like) genes in both a brachiopod and a polychaete annelid, which supports the lophotrochozoan assemblage, and a distinct posterior Hox gene shared by a priapulid, a nematode and the arthropods, which supports the ecdysozoan clade.
life.nthu.edu.tw /~b830356/LS6901/2.html   (215 words)

  
 Brainstorms: Nelson and Ross: Problems with Characterizing the Protostome-Deuterostome Ancestor
One of the central difficulties is characterizing the common ancestor of the protostomes and deuterostomes.
We argue that an unresolved conceptual puzzle has plagued the many attempts to describe this Urbilaterian, or, in Erwin and Davidson’s (2002) terminology, the protostome-deuterostome ancestor (PDA).
We were supposed to imagine that this was the egg of the hypothetical pre-Cambrian common ancestor of both protostomes and deuterostomes.
www.iscid.org /boards/ubb-get_topic-f-6-t-000536.html   (2588 words)

  
 Testing the New Animal Phylogeny: First Use of Combined Large-Subunit and Small-Subunit rRNA Gene Sequences to Classify ...
sequenced LSU and SSU genes from the protostomes Caenorhabditis
protostomes, and Ecdysozoa (that is, the SSU index exceeds the
Note that the position of chaetognaths within protostomes is treated as uncertain (?).
mbe.oxfordjournals.org /cgi/content/full/19/3/289   (6226 words)

  
 The last common bilaterian ancestor -- Erwin and Davidson 129 (13): 3021 -- Development
protostomes and deuterostomes is a problem of enormous interest,
(A) A representative metazoan phylogeny pre-1995 showing the division of metazoa into the diploblasts, acoelomates and pseudocoelomates, and the coelomate protostomes and deuterostomes; note the intermediate position of the lophophorate phyla.
protostome and deuterostome forms must have existed in the evolutionary
dev.biologists.org /cgi/content/full/129/13/3021   (7269 words)

  
 Phylogenetic position of phylum Nemertini, inferred from 18S rRNA sequences: molecular data as a test of morphological ...
whether nemertines lie within a protostome coelomate clade, as suggested by
inclusion of the nemertine within a protostome- coelomate clade that falls
The relationships among the protostome coelomates cannot be reliably
mbe.oxfordjournals.org /cgi/content/abstract/9/2/235   (471 words)

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