Lophotrochozoa
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| Lophotrochozoa Fossil range: Early Cambrian - Recent |
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 Caribbean Reef Squid or Sepioteuthis sepioidea is a complex lophotrochozoan.
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The Lophotrochozoa (pronounced /ləˌfɒtrɵkɵˈzoʊ.ə/, "crest-bearing animals") are a major grouping of protostome animals. The taxon was introduced in 1995 in a paper by Kenneth M Halanych et al. based on molecular data. Molecular evidence such as a result of studies of the evolution of small-subunit ribosomal RNA (rRNA) supports the monophyly of the phyla listed in the infobox shown at right.[1]
[edit] Terminology
The word "lophotrochozoan" is sometimes equated with spiralian.[2] When used in a broader sense (sensu lato), it can include rotifers and platyhelminthes.[3] When used sensu stricto, it refers to a subgroup of Spirilia.
[edit] Groups
The Lophotrochozoa comprise two groups, the trochozoans and the lophophorata. The exact relationships between the different phyla are not entirely certain. However, it appears that neither the lophophorates nor the trochozoa are monophyletic groups by themselves, but are mixed together.[4]
- Trochozoans produce trochophore larvae, which have two bands of cilia around their middle.[4] Previously these were treated together as the Trochozoa, together with the arthropods, which do not produce trochophore larvae but were considered close relatives of the annelids because they are both segmented. However, they show a number of important differences, and the arthropods are now placed separately among the Ecdysozoa. The Trochozoa include the Nemertea, Mollusca, Sipuncula, Echiura, Pogonophora and Annelida.[4]
- The Lophophorata are united by the presence of a lophophore, a fan of ciliated tentacles surrounding the mouth, and so were treated together as the lophophorates. They are unusual in showing radial cleavage, and some authors considered them deuterostomes, before RNA trees placed them together with the trochozoans. The Lophophorata include the Bryozoa, Entoprocta, Phoronida, and Brachiopoda.[4]
Other phyla are included on the basis of molecular data.
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[edit] References
- ^ Philippe, Hervé, Nicolas Lartillot1 and Henner Brinkmann. (2005) "Multigene Analyses of Bilaterian Animals Corroborate the Monophyly of Ecdysozoa, Lophotrochozoa, and Protostomia." Molecular Biology and Evolution 2005 22(5):1246-1253; doi:10.1093/molbev/msi111. Found at [1]
- ^ Giribet G (April 2008). "Assembling the lophotrochozoan (=spiralian) tree of life". Philos. Trans. R. Soc. Lond., B, Biol. Sci. 363 (1496): 1513–22. doi:. PMID 18192183. PMC: 2614230. http://rstb.royalsocietypublishing.org/cgi/pmidlookup?view=long&pmid=18192183.
- ^ "Explanations.html". http://science.kennesaw.edu/~jdirnber/InvertZoo/Tree/Explanations.html. Retrieved on 2009-06-28.
- ^ a b c d Introduction to the Lophotrochozoa - accessed 8 August 2008
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Wikispecies has information related to: Lophotrochozoa/Spiralia |
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