Part Six - The Evolution of Diversity 55

31. Animal Origins and the Evolution of Body Plans 670

31.1 What Evidence Indicates the Animals Are Monophyletic? 671 Animal monophyly is supported by gene sequences and morphology 671 Developmental patterns show evolutionary relationships among animals 672 31.2 What Are the Features of Animal Body Plans? 674 Most animals are symmetrical 674 The structure of the body cavity influences movement 674 Segmentation improves control of movement 675 Appendages enhance locomotion 676 31.3 How Do Animals Get Their Food? 676 Filter feeders capture small prey 676 Herbivores eat plants 677 Predators capture and subdue large prey 678 Parasites live in or on other organisms 679 31.4 How Do Animal Life Cycles Differ? 679 All life cycles have at least one dispersal stage 680 No life cycle can maximize all benefits 680 Parasite life cycles evolve to facilitate dispersal and overcome host defenses 681 31.5 What Are the Major Groups of Animals? 682 Sponges are loosely organized animals 683 Ctenophores are radially symmetrical and diploblastic 684 Cnidarians are specialized carnivores 685