Table of Contents

1 Environmental Considerations 2 Invertebrate Classification and Relationships 3 The Protozoans 4 The Poriferans and Placozoans 5 Introduction to the Hydrostatic Skeleton 6 The Cnidarians 7 The Ctenophores 8 The Platyhelminthes 9 The Mesozoans: Possible Flatworm Relatives 10 The Rotifers and Acanthocephalans 11 The Nemertines 12 The Molluscs 13 The Annelids and Sipunculans 14 The Arthropods 15 Two Phyla of Likely Arthropod Relatives: Tardigrada and Onychophora 16 The Nematodes 17 Four Phyla of Likely Nematode Relatives: Nematomorpha, Priapulida, Kinorhyncha, and Loricifera 18 Five Phyla (Plus One Species) of Uncertain Affiliation: Myxozoa, Gnathostomulida, Gastrotricha, Xenoturbella bocki, Chaetognatha, and Cyliophora 19 The Lophophorates (Phoronids, Brachiopods, Bryozoans) and Entoprocts 20 The Echinoderms 21 The Hemichordates 22 The Nonvertebrate Chordates 23 Invertebrate Reproduction and Development--An Overview