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From: purves@muddcs.UUCP (Bill Purves)
Newsgroups: net.bio
Subject: Re: Do ants have hearts?
Message-ID: <326@muddcs.UUCP>
Date: Fri, 14-Jun-85 14:19:54 EDT
Article-I.D.: muddcs.326
Posted: Fri Jun 14 14:19:54 1985
Date-Received: Tue, 18-Jun-85 04:33:25 EDT
Distribution: net
Organization: Harvey Mudd College, Claremont, CA
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*** REPLACE THIS LINE WITH YOUR PHYLUM ***
Jeff Fields asks:

     > How is food and oxygen circulated in invertebrates.

He and his friends were wondering whether ants have hearts, how worms breathe,
and so forth.

The main question is trickier than it seems, because there are MANY kinds of
invertebrates, living in different environments and solving different 
problems.

Ants (and other arthropods) DO have hearts -- tubes open at both ends, that
pulse and squoosh fluid out both ends into an open system not contained in
vessels.  The heart just sort of stirs things up.  Flatworms have no
circulatory system.  Round worms have blood in a general body cavity that gets
stirred up by the overall movement of the worm.  Earthworms have TWO hearts
in EACH body segment.  Squids have THREE hearts--a systemic heart and two
auxiliary hearts that serve the gills.  "Breathing" in worms is various --
some marine worms have gills that rival peacock tails in their ornateness.

In general, refer to any good intro biology text.  For obvious reasons, I am
partial to LIFE, by Purves and Orians (Sinauer Associates, 1983) . . .
-- 
Bill Purves                              (714) 621-8021                 
Depts. of Biology and Computer Science   {cepu,ihnp4,ucbvax}!ucla-cs!purves
Harvey Mudd College                      purves@UCLA-LOCUS.ARPA   (old system)
Claremont, CA 91711                      purves@LOCUS.UCLA.EDU    (new ARPA)
      "Those Who Are Ignorant of Biology Are Destined to Repeat It"