[Taxacom] motile "Animalia"

Kenneth Kinman kennethkinman at webtv.net
Thu Jan 14 20:45:59 CST 2010


Hi Stephen,
     I agree, motility is poor character, as is multicellularity (even
filamentous cyanobacteria could be regarded as multicellular).  Haeckel
solved this way back in the 1860s by rejecting the animal/plant
dichotomy and recognizing a separate Kingdom Protista.  Eventually
(1930s?) the prokaryotes were split off as a 4th Kingdom.  
       Whether splitting off Eumycota (as "Fungi") as a 5th Kingdom did
more harm than good is debatable, since it too often included a
polyphyletic assemblage of saprophytes.  In any case, it opened a
slippery slope of even worse ideas for additional Kingdoms.  The utility
of a 4 or 5 Kingdom classification has therefore been largely lost,
mainly because Kingdom Protista is paraphyletic and the campaign to
brand such groups as unnatural.
        Anyway, ever since the Protozoa were transferred to Kingdom
Protista, there has been little inclination to return them to the clade
"Animalia", which many began to call by the more precise term "Metazoa".
Both the formal name "Animalia" and the common name "animals" are just
too imprecise and loaded with historical baggage, at least in my
opinion.  
         ----------Ken Kinman
----------------------------------------------------------
Stephen wrote:
 Very bad "definition" by cladistic standards: non-photosynthetic =
plesiomorphy, motility = homoplasy 
add multicellular (=apomorphy, though biphyletic - also an apomorphy of
plants) and you get a better definition, equivalent to Metazoa (with the
Parazoa thrown in while you blink), and probably monophyletic, but quite
apart from any issues to do with vernacular names, should we call such a
clade (scientific name) Animalia or Metazoa? 






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