Difference between revisions of "Invertebrate" - New World Encyclopedia

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'''Invertebrate''' is a term coined by [[Jean-Baptiste Lamarck]] to describe any [[animal]] without a [[spinal column]]. It therefore includes all animals except [[vertebrate]]s ([[fish]], [[reptile]]s, [[amphibian]]s, [[bird]]s and [[mammal]]s).
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'''Invertebrate''' is a term coined by [[Jean-Baptiste Lamarck]] to describe any [[animal]] without a [[spinal column]]. The group includes 97% of all animal [[species]]—all animals except [[vertebrate]]s ([[fish]], [[reptile]]s, [[amphibian]]s, [[bird]]s and [[mammal]]s).
  
Lamarck divided these animals into two groups, the [[Insect]]a and the [[Vermes]], but now, they are classified into over 30 [[phylum (biology)|phyla]], from simple organisms such as [[sponge]]s and [[flatworm]]s to complex animals such as [[arthropod]]s and [[mollusk]]s.
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Lamarck divided these animals into two groups, the [[Insect]]a and the [[Vermes]], but they are now classified into over 30 [[phylum (biology)|phyla]], from simple organisms such as [[sponge]]s and [[flatworm]]s to complex animals such as [[arthropod]]s and [[Mollusca|molluscs]].
  
Since invertebrates include all animals except a certain group, invertebrates form a [[paraphyletic]] group, but, despite not forming a "natural group" (that is, [[monophyletic]]), "invertebrate" is still a widely used term.  Invertebrates include 97% of all animal [[species]].
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Since invertebrates include all animals except a certain group, invertebrates form a [[paraphyletic]] group. (For a full list of animals considered to be invertebrates, see [[animal]].) All the listed phyla are invertebrates along with two of the three [[subphylum|subphyla]] in Phylum [[chordate|Chordata]]: [[Urochordata]] and [[Cephalochordata]]. These two, plus all the other known invertebrates, have only one cluster of [[Hox genes]], while the vertebrates have duplicated their original cluster more than once.
  
For a full list of animals considered to be invertebrates, see [[animal]]. All the listed phyla are invertebrates along with two of the three [[subphylum|subphyla]] in Phylum [[chordate|Chordata]]: [[Urochordata]] and [[Cephalochordata]]. These two, plus all the other known invertebrates, have only one cluster of [[Hox genes]], while the vertebrates have duplicated their original cluster more than once.
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==Phyla and common examples==
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*[[Porifera]] — sponges
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*[[Cnidarians]] — jellyfish
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*[[Platyhelminthes]] — flatworms
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*[[Nematoda]] — roundworms
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*[[Annelida]] — earthworms
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*[[Echinodermata]] — sea star, sea urchins, sea cucumbers
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*[[Mollusc]]a — squid, snails
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*[[Arthropod]]a — insects, ticks, spiders, grasshoppers, lobsters, crabs
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*[[Bryozoa]] — moss animals, sea mats (occasionally resemble corals)
  
 
==External links==
 
==External links==
* [http://reference.allrefer.com/encyclopedia/categories/invertz.html Invertebrate Zoology]
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*{{cite book |author=A. R. Maggenti & S. Gardner |url=http://digitalcommons.unl.edu/onlinedictinvertzoology/ |title=Online Dictionary of Invertebrate Zoology |year=2005}}
*[http://digitalcommons.unl.edu/onlinedictinvertzoology/ ''Online Dictionary of Invertebrate Zoology'']
 
*[http://www.goliathus.cz/en/museum-homepage-0.html Online insect museum] of many invertebrates, provided by [http://www.goliathus.cz/ goliathus.cz].
 
  
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[[Category:Life sciences]]
 
[[Category:Life sciences]]

Revision as of 20:49, 6 November 2006

Invertebrate is a term coined by Jean-Baptiste Lamarck to describe any animal without a spinal column. The group includes 97% of all animal species—all animals except vertebrates (fish, reptiles, amphibians, birds and mammals).

Lamarck divided these animals into two groups, the Insecta and the Vermes, but they are now classified into over 30 phyla, from simple organisms such as sponges and flatworms to complex animals such as arthropods and molluscs.

Since invertebrates include all animals except a certain group, invertebrates form a paraphyletic group. (For a full list of animals considered to be invertebrates, see animal.) All the listed phyla are invertebrates along with two of the three subphyla in Phylum Chordata: Urochordata and Cephalochordata. These two, plus all the other known invertebrates, have only one cluster of Hox genes, while the vertebrates have duplicated their original cluster more than once.

Phyla and common examples

External links

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