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CHAPTER 31 Animal Origins and Lophotrochozoans

CHAPTER 31 Animal Origins and Lophotrochozoans. Chapter 31: Animal Origins and Lophotrochozoans. Descendants of a Common Ancestor The Animal Way of Life Clues to Evolutionary Relationships among Animals Body Plans Are Basic Structural Designs Sponges: Loosely Organized Animals.

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CHAPTER 31 Animal Origins and Lophotrochozoans

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  1. CHAPTER 31Animal Origins and Lophotrochozoans

  2. Chapter 31: Animal Origins and Lophotrochozoans Descendants of a Common Ancestor The Animal Way of Life Clues to Evolutionary Relationships among Animals Body Plans Are Basic Structural Designs Sponges: Loosely Organized Animals

  3. Chapter 31: Animal Origins and Lophotrochozoans Cnidarians: Cell Layers and Blind Guts Ctenophores: Complete Guts and Tentacles The Evolution of Bilaterally Symmetrical Animals Protostomes and Deuterostomes: An Early Lineage Split

  4. Chapter 31: Animal Origins and Lophotrochozoans Simple Lophotrochozoans Lophophorates: An Ancient Body Plan Spiralians: Wormlike Body Plans Segmented Bodies: Improved Locomotion

  5. Descendants of a Common Ancestor • All members of the kingdom Animalia are believed to have a common flagellated protist ancestor. 5

  6. Descendants of a Common Ancestor • The specialization of cells made possible the complex, multicellular body plan of animals. 6

  7. The Animal Way of Life • Animals obtain their food—complex organic molecules—by active expenditure of energy. 7

  8. Clues to Evolutionary Relationships among Animals • Morphological, developmental, and molecular data support similar animal phylogenies. 8

  9. Clues to Evolutionary Relationships among Animals • An animal’s body cavity is correlated with its ability to move. • Based on this, animals are classified as acoelomates, pseudocoelomates, or coelomates. Review Figure 31.1 9

  10. figure 31-01.jpg Figure 31.1 Figure 31.1

  11. Clues to Evolutionary Relationships among Animals • The two major animal lineages—protostomes and deuterostomes—are believed to have separated early in animal evolution. Review Figure 31.2 11

  12. figure 31-02.jpg Figure 31.2 Figure 31.2

  13. Body Plans Are Basic Structural Designs • Most animals have radial or bilateral symmetry. • Radially symmetrical animals move slowly, if at all. • Those with bilateral symmetry have more rapid movements and sensory organs. Review Figure 31.3 13

  14. figure 31-03.jpg Figure 31.3 Figure 31.3

  15. Sponges: Loosely Organized Animals • Sponges are simple animals that lack cell layers and body symmetry, but have several cell types. 15

  16. Sponges: Loosely Organized Animals • Sponges feed via choanocytes, feeding cells that filter out small organisms and nutrients. Review Figure 31.4 16

  17. figure 31-04.jpg Figure 31.4 Figure 31.4

  18. Cnidarians: Cell Layers and Blind Guts • Cnidarians are radially symmetrical and have two cell layers. • With nematocyst-studded tentacles, they capture prey larger and more complex than themselves. Review Figure 31.7 18

  19. figure 31-07.jpg Figure 31.7 Figure 31.7

  20. Cnidarians: Cell Layers and Blind Guts • Most cnidarian life cycles have a sessile polyp and a free-swimming, sexual medusa stage, but some species lack one of the stages. Review Figures 31.8, 31.9, 31.10 20

  21. figure 31-08.jpg Figure 31.8 Figure 31.8

  22. figure 31-09.jpg Figure 31.9 Figure 31.9

  23. figure 31-10.jpg Figure 31.10 Figure 31.10

  24. Ctenophores: Complete Guts and Tentacles • Ctenophores, descendants of the first split in the lineage of bilaterally symmetrical animals, are marine carnivores with simple life cycles. Review Figure 31.12 24

  25. figure 31-12.jpg Figure 31.12 Figure 31.12

  26. The Evolution of Bilaterally Symmetrical Animals • Common ancestors of bilateral animals, urbilaterians, were probably simple, bilaterally symmetrical animals composed of flattened masses of cells. 26

  27. Protostomes and Deutero- stomes: An Early Lineage Split • Protostomes and deuterostomes have been evolving separately since the Cambrian period. • Protostomes have a ventral nervous system, paired nerve cords, and larvae with compound cilia. • Deuterostomes have a dorsal nervous system and larvae with single cilia. 27

  28. Protostomes and Deutero-stomes: An Early Lineage Split • Protostomes split into two major classes—lophotrochozoans and ecdysozoans. Review Figure 31.14 28

  29. figure 31-14.jpg Figure 31.14 Figure 31.14

  30. Simple Lophotrochozoans • Flatworms have no body cavity, lack organs for oxygen transport, have one gut entrance, and move via cilia. • Many species are parasitic. Review Figures 31.15, 31.16 30

  31. figure 31-15.jpg Figure 31.15 Figure 31.15

  32. figure 31-16.jpg Figure 31.16 Figure 31.16

  33. Simple Lophotrochozoans • No larger than many ciliated protists, rotifers have highly developed internal organs. Review Figure 31.17 33

  34. figure 31-17.jpg Figure 31.17 Figure 31.17

  35. Lophophorates: An Ancient Body Plan • The lophotrochozoan lineage split into two branches, the lophophorates and the spiralians. 35

  36. Lophophorates: An Ancient Body Plan • The lophophore dominates the anatomy of many lophophorate animals. Review Figure 31.18 36

  37. figure 31-18.jpg Figure 31.18 Figure 31.18

  38. Lophophorates: An Ancient Body Plan • Bryozoans are colonial lophophorates that can move their lophophores. Review Figure 31.20 38

  39. figure 31-20.jpg Figure 31.20 Figure 31.20

  40. Lophophorates: An Ancient Body Plan • Brachiopods were much more abundant in the past than they are today. 40

  41. Spiralians: Wormlike Body Plans • The spiralian lineage gave rise to many phyla, most of whose members have wormlike body forms. 41

  42. Spiralians: Wormlike Body Plans • Ribbon worms have a complete digestive tract and capture prey with a reversible proboscis. Review Figure 31.22 42

  43. figure 31-22.jpg Figure 31.22 Figure 31.22

  44. Segmented Bodies: Improved Locomotion • Annelids are a diverse group of segmented worms that live in marine, freshwater, and terrestrial environments. Review Figure 31.23 44

  45. figure 31-23.jpg Figure 31.23 Figure 31.23

  46. Segmented Bodies: Improved Locomotion • Mollusks evolved from segmented ancestors. • The three basic components of the molluscan body plan are the foot, mantle, and visceral mass. Review Figure 31.25 46

  47. figure 31-25a.jpg Figure 31.25 – Part 1 Figure 31.25 – Part 1

  48. figure 31-25b.jpg Figure 31.25 – Part 2 Figure 31.25 – Part 2

  49. Segmented Bodies: Improved Locomotion • The molluscan body plan yields a diverse array of animals that superficially appear very different from one another. 49

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