[Taxacom] Animalia or Metazoa?

Kenneth Kinman kennethkinman at webtv.net
Fri Jul 24 08:53:49 CDT 2009

Stephen and Tony,
      Well, I think a more relevant use of Google might be to search
Google Scholar.  Doing that we get less than 26,000 hits for Animalia,
while we get over 39,000 hits for Metazoa.  That gives us a much broader
view than just quoting Margulis or Whitaker (who do not represent the
majority of scholars by this test). Therefore, the popularity (usage)
criterion is a draw, most scholars seem to prefer Metazoa, while the
broader population seems to gravitate more toward Animalia.  
      So it is more a question of semantics and/or precision.  The name
Metazoa refers to a precise clade which almost everyone agrees contains
sponges plus eumetazoans (precise content), and the name Metazoa means
"higher animals" (literally precise).      
       Animalia (animals) literally refers to organisms which "breathe"
(get energy from respiration), as opposed to organisms which generally
get their energy directly from photosynthesis.  Most protozoans have
mitochondria and therefore perform respiration, and are therefore
literally animals.  And as a more practical matter, if you use Animalia
as a synonym of Metazoa, it leaves us without a good name for that
broader Protozoa + Metazoa grouping (both of which use respiration).
Perhaps that's yet another reason that a majority of scholars prefer
         -------Ken Kinman

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