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Echiura History +

Cutlereb at aol.com Cutlereb at aol.com
Fri Nov 12 13:53:48 EST 1999


     It might be of interest to provide just a wee bit of historical 
background on when/why this group of worms was upgraded to a phylum - 

Quote from Stephen & Edmonds, 1972:343. 

   The Echiuroidea was established as a phylum largely as a
result of the studies of Newby (1940) on the embryology and
development of Urechis caupo. He showed that annelids and
echiurans differ considerably in their mode of development, that
the mesodermal bands of developing echiurans show no trace of
segmentation and that echiurans are no more related to annelids
than they are to molluscs. He advocated that the group be
considered as forming a separate phylum. The phyletic status of
the group is now generally accepted.  


      Now different data from the same species is used to 'downgrade' it....

	It was very good news to learn of Mr. Hessling's work and we look 
forward to seeing the results.  I do have no problem accepting the 
concept of our arbitrary and perhaps artificial ways of grouping and 
ranking objects - natural or man-made.  It seems to me to be a 
necessary 'evil' as Geoff suggests.  Where (and how) does the line 
between natural and unnatural groups get drawn? (Not a new or original 
question)  It's also my perception that science operates by building a 
convincing case, based on testable hypothesis - not by declarations from 
'on high'.   

	Maybe the earlier 'upgrade' based on one aspect of their 
development was not well founded - but - maybe not.   Perhaps a session 
at the Iceland meetings where this could be discussed face-to-face would 
be healthy, stimulating & maybe even fun??    


Edward B. Cutler, PhD
Department of Invertebrate Zoology
Museum of Comparative Zoology
Harvard University
Cambridge, MA   02138
Telephone: 617-738-0107       e-mail:  CutlerEB at aol.com

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