[net.bio] Do ants have hearts?

jefff@cadovax.UUCP (Jeffery H. Fields) (06/11/85)

Here is a question for the entomologists and the invertebrate zoologists:

     How is food and oxygen circulated in invertebrates?

This question came up at lunch the other day.  It started with, "Do ants have
hearts?" and progressed onto, "How do worms breathe?"  Any shared knowledge on
this topic would be greatly appreciated.

-- 

				Jeff Fields
				{ucbvax,ihnp4,decvax}!trwrb!cadovax!jefff

purves@muddcs.UUCP (Bill Purves) (06/14/85)

*** 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"

lonetto@phri.UUCP (Michael Lonetto) (06/18/85)

> 
> Here is a question for the entomologists and the invertebrate zoologists:
> 
>      How is food and oxygen circulated in invertebrates?
                                            ^^^^^^^^^^^^^

The question is a little broad as phrased.  Since the subjuct line mentioned
ants:

Insects have an "open" circulation system consisting of "hemolymph",
(which serves the purposes of blood) which is circulated by a simple
heart and dorsal artery.  The artery leads to the ends of the organism
where the "blood" flows into the body cavity and, eventually, back to
the heart(which has a direct input).  Oxygen exchange is accomplished by
a system of trachea which branch throughout the body and are connected
to the outside air by spiracles, which are small openings in the
exoskeleton.  Since oxygen and CO2 don't have to diffuse far from the
trachea a fairly simple circulatory system is quite efficient.  

Incidentally, this is one of the factors limiting the size of insects.
Aren't you glad?

Michael Lonetto   PHRI

allegra!phri!lonetto
-- 
Michael Lonetto  PHRI  NYC  (allegra!phri!lonetto)

"Some win, Some lose, Some refuse to play"