Invertebrate
An invertebrate is a Animal deprived of Spinal column. It can be plain or pluricellular. In term of number of Species S, the invertebrates constitute the greatest part of the known Biodiversité; on 1,7 to 1,8 million species listed in 2005 (according to the criteria retained for their classification), one finds approximately 990.000 invertebrates, 360.000 plants and micro-organisms, and only 45.000 vertebrate. It is probably the group which, with the micro-organisms, was the least best inventoried, because the invertebrates are often of small size and discreetly live, in the seas, the sediments, the grounds or the Nécromasse (of which the Deadwood). The Insectes are the best known ones.
The invertebrates were classified in several subsets:
-
the protozoon S
- the Spongiaire S
- the Cnidaire S and the Cténaire S
- the Plathelminthe S
- the Némathelminthe S
- the Annélide S
- the Mollusc S
- the Arthropod S
- echinodermatous S
The distinction between Vertebrate S and invertebrates was initiated by Jean-Baptiste de Lamarck. The group of the invertebrates not being Monophylétique, its value is called into question in recent classifications. It makes it possible nevertheless to distinguish the subphylum to which belong the men (the vertebrate ones) of all the other animals in a manner anthropocentrist.
Simple: Invertebrate
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