An Introduction to Animal Diversity

1. An Introduction to Animal Diversity What Is an Animal? An Overview of Animal Phylogeny and Diversity The Origins of Animal Diversity

2. What Is an Animal? • Multicellular, eukaryotic, heterotrophic, ingestion feeder, stores glycogen, nervous system, no cell walls, muscle system, sexual, flagellated sperm, dominant diploid • Zygotecleavageblastulagastrula larva with metamorphosis

3. Figure 32.1 Early embryonic development (Layer 1)

6. Overview of Animal Diversity and Phylogeny • Diversified during Precambrian and Cambrian periods • Monophyletic • Parazoans-first branch, lack true tissues • Radiata and bilateria two major branches of Eumetazoa • Evolution of body cavities • Protostomes and deuterostomes

8. Parazoa • Sponges • “beside the animals” • Simple aquatic and marine forms

9. Eumetazoa Two major branches: • 1. Radiata-radial symmetry, top and bottom, no front, back, or sides, diploblastic larva • 2. Bilateria-bilateral symmetry, triploblastic, cephalization

11. Importance of Coelom • Acoelomates-no body cavity, Platyhelminthes • Pseudocoelomates-fluid filled body cavity, partially lined with mesoderm, Nematoda • Coelomates-fluid filled, completely lined with mesoderm, Annelida • Coelom-body cavity that protects internal organs

13. Protostomes: Mollusks, Annelids, Arthropods Spiral cleavage Determinate cleavage Blastopore forms the mouth schizocoelous Deuterostomes: Echinoderms and Chordates Radial cleavage Indeterminate cleavage Blastopore forms the anus Enterocoelous Protostomes and Deuterostomes

15. The Origins of Animal Diversity • Colonial protist origin during Cambrian Explosion • Evidence from fossil beds: Burgess Shale, Yunnan region, Greenland • Why such rapid diversification? 1. Adaptive radiation 2. Predator-prey relationships 3. Higher concentration of oxygen

16. Videos and Websites • http://animaldiversity.ummz.umich.edu/site/index.html