REGARDING           Respiration and invertebrates
 
In response to a previous post of mine, Dave Goble writes:
"Crabs are in the phylum of Crustacea, and have 30,500 species of
these invertebrates.
      If crabs had gills when they dig into the sand their gills would be
covered by sand grains and suffocation would occur.
      The insect species from bees, flies, and mosquitoes are of the same
principle as the rest of the invertebrate class.
        The breathing systems are all the same, with slightly evolved
changes for each species.
        Fish and all other gill breathing animals are not in the
invertebrate class. As they are vertebrates."
 
This is probably not the best place for this discussion, but a few basic
facts of biology should be gotten straight.  Arthropoda is the *phylum* that
includes the *class* Crustacea (crabs, barnacles, etc.) as well as the
*class* Insecta (bees, mosquitos, etc.).
 
Respiratory systems of any organism must be adapted to the living habits of
that organism, regardless of its classification.  Therefore, marine animals,
such as crabs (Crustacea) as well as fishes (Vertebrata) breathe with gills
of one type or another, whether they are free swimming or burrowing species.
Land animals are equipped with different respiratory structures, for bees
(Insecta) have a tracheal tube system and mammals (Vertebrata) have lungs.
Let's not confuse taxonomic with anatomic matters.
 
Ted Fischer