Invertebrates 2nd edition presents a modern survey of the 34 animal phyla (plus the Protista) and serves as both a college course text and a reference on invertebrate biology. It is organized around the themes of bauplans (body plans) and evolution (phylogenetics). Detailed classifications, phylogenetic trees, and references for all phyla are provided. The text is accompanied by detailed line drawings and - new to this edition - four-colour photographs. Other key changes from the 1st edition (1990) include: the incorporation of all the new developments in phylogenetics, developmental biology and molecular genetics; major changes at the highest levels among the invertebrates; three phyla that appeared in the original book Pentastomida, Pogonophora and Vestimentifera no longer exist, and an entire new phylum, Cycliophora, has been erected. Moreover, this edition discusses recent work in molecular systematics, and there is a large new section on Kingdom Protista (replacing Protozoa) containing new contemporary views of these organisms (arranged in 17 phyla).