MadSci Network: General Biology

Re: How is a sarcodine protozoan different from other protozoans

Date: Tue Jan 25 14:43:55 2000
Posted By: Dean Cliver, Faculty, Food Safety Unit, Uiversity of California, Davis
Area of science: General Biology
ID: 948427488.Gb

	Some time after Noah landed, some his descendants decided they 
should classify all living things.  Many classification systems have been 
tried.  During the 18th century, a Swede named Karl Linne (who called 
himself "Carolus Linnaeus"  that was when real scientists communicated in 
Latin) organized the system that is used today.  People who classify living 
things call themselves "taxonomists."  This is one of the few things on 
which they seem to agree.  
	I am neither a protozoologist nor a taxonomist; but I am a 
scientist, even though I don't know much Latin.  I went to my university 
library and did a brief search through books about Protozoa.  I could soon 
appreciate your problem  some of the books that claimed to cover all of 
Protozoa did not mention sarcodines, nor the official group Sarcodina.  
	But one did: in Lee, J. J., S. H. Hutner, and E. C. Bovee 
(editors), An Illustrated Guide to the Protozoa, Society of 
Protozoologists, Lawrence, Kansas, 1985, there was a classification scheme 
that included the Sarcodina.  Here's how it goes  Kingdom Protista 
(one-celled organisms with true nuclei); Subkingdom Protozoa (protists that 
mostly don't have photosynthetic apparatus?); Phylum Sarcomastigophora 
(protozoa that have flagella, plus the "sarcodines"); Subphylum Sarcodina 
("form so-called pseudopodia, of one type or another, in their trophic 
states," any flagella usually occur in temporary stages, may have a 
skeleton or "test," usually free-living [i.e., not parasitic], etc.).  
Subordinate classifications are Superclass, Class, Order, Family, Genus, 
and species; there is an endless array of these among the Sarcodina.  
	As you probably know, pseudopodia are the little oozy projections 
that amoebae put out in front of them when they are trying to go somewhere. 
 Not surprisingly, the amoebae (many varieties in several classification 
levels, including the genus Amoeba) are among the Sarcodina.  Their 
"trophic state" is when they are actively moving about and engulfing stuff 
as food; alternately, they have a resting phase called a "cyst" that more 
or less hibernates when times are hard.  To be classified as Sarcodina, the 
other, non-amoebae must form pseudopodia sometime during their lives.  Some 
taxonomists don't think this is a valid way to classify protozoa  they 
might be more impressed if these organisms traveled on in-line skates.  I 
would guess that the sarcodines are not too impressed by taxonomists, 
	I hope this is most of the information you needed.  At least you've 
learned that taxonomists are not the people who stuff dead animals.

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