A
triploblastic organism which does not have an internal
body cavity other than the
gut. The area between the gut and the organism's outer body wall is completely filled with
tissue derived from the
mesoderm. The term is used to classify
multicellular animals by
developmental pattern.
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.