Examine the following sections:
Diversity/Invertebrates/Characteristics
5.137 Multicellular Heterotrophs
5.138 Body Symmetry
5.139 Type of Symmetry
5.140 Coelom
5.141 Embryonic Tissue Layers
5.142 Protostomes and Deuterostomes
5.143 Taxa Chart
An Uproar Over Invertebrate Phylogeny. (Page 634)