1. Chapter 31: Animal Origins and Lophotrochozoans CHAPTER 31 Animal Origins and Lophotrochozoans

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

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

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

5. Chapter 31: Animal Origins and Lophotrochozoans Descendants of a Common Ancestor All members of the kingdom Animalia are believed to have a common flagellated protist ancestor.All members of the kingdom Animalia are believed to have a common flagellated protist ancestor.5

6. Chapter 31: Animal Origins and Lophotrochozoans Descendants of a Common Ancestor The specialization of cells made possible the complex, multicellular body plan of animals.The specialization of cells made possible the complex, multicellular body plan of animals.6

7. Chapter 31: Animal Origins and Lophotrochozoans The Animal Way of Life Animals obtain their food—complex organic molecules—by active expenditure of energy.Animals obtain their food—complex organic molecules—by active expenditure of energy.7

8. Chapter 31: Animal Origins and Lophotrochozoans Clues to Evolutionary Relationships among Animals Morphological, developmental, and molecular data support similar animal phylogenies.Morphological, developmental, and molecular data support similar animal phylogenies.8

9. Chapter 31: Animal Origins and Lophotrochozoans Clues to Evolutionary Relationships among Animals An animal’s body cavity is correlated with its ability to move.An animal’s body cavity is correlated with its ability to move. Based on this, animals are classified as acoelomates, pseudocoelomates, or coelomates.Based on this, animals are classified as acoelomates, pseudocoelomates, or coelomates. Review Figure 31.1 31.1 9

10. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.1 figure 31-01.jpg

11. Chapter 31: Animal Origins and Lophotrochozoans Clues to Evolutionary Relationships among Animals The two major animal lineages— protostomes and deuterostomes—are believed to have separated early in animal evolution.The two major animal lineages— protostomes and deuterostomes—are believed to have separated early in animal evolution. Review Figure 31.2 31.2 11

12. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.2 figure 31-02.jpg

13. Chapter 31: Animal Origins and Lophotrochozoans Body Plans Are Basic Structural Designs Most animals have radial or bilateral symmetry.Most animals have radial or bilateral symmetry. Radially symmetrical animals move slowly, if at all.Radially symmetrical animals move slowly, if at all. Those with bilateral symmetry have more rapid movements and sensory organs.Those with bilateral symmetry have more rapid movements and sensory organs. Review Figure 31.3 31.3 13

14. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.3 figure 31-03.jpg

15. Chapter 31: Animal Origins and Lophotrochozoans Sponges: Loosely Organized Animals Sponges are simple animals that lack cell layers and body symmetry, but have several cell types.Sponges are simple animals that lack cell layers and body symmetry, but have several cell types.15

16. Chapter 31: Animal Origins and Lophotrochozoans Sponges: Loosely Organized Animals Sponges feed via choanocytes, feeding cells that filter out small organisms and nutrients.Sponges feed via choanocytes, feeding cells that filter out small organisms and nutrients. Review Figure 31.4 31.4 16

17. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.4 figure 31-04.jpg

18. Chapter 31: Animal Origins and Lophotrochozoans Cnidarians: Cell Layers and Blind Guts Cnidarians are radially symmetrical and have two cell layers.Cnidarians are radially symmetrical and have two cell layers. With nematocyst-studded tentacles, they capture prey larger and more complex than themselves.With nematocyst-studded tentacles, they capture prey larger and more complex than themselves. Review Figure 31.7 31.7 18

19. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.7 figure 31-07.jpg

20. Chapter 31: Animal Origins and Lophotrochozoans 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.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 31.831.931.1031.831.931.1020

21. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.8 figure 31-08.jpg

22. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.9 figure 31-09.jpg

23. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.10 figure 31-10.jpg

24. Chapter 31: Animal Origins and Lophotrochozoans 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.Ctenophores, descendants of the first split in the lineage of bilaterally symmetrical animals, are marine carnivores with simple life cycles. Review Figure 31.12 31.12 24

25. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.12 figure 31-12.jpg

26. Chapter 31: Animal Origins and Lophotrochozoans The Evolution of Bilaterally Symmetrical Animals Common ancestors of bilateral animals, urbilaterians, were probably simple, bilaterally symmetrical animals composed of flattened masses of cells.Common ancestors of bilateral animals, urbilaterians, were probably simple, bilaterally symmetrical animals composed of flattened masses of cells.26

27. Chapter 31: Animal Origins and Lophotrochozoans Protostomes and Deutero- stomes: An Early Lineage Split Protostomes and deuterostomes have been evolving separately since the Cambrian period.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.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.Deuterostomes have a dorsal nervous system and larvae with single cilia.27

28. Chapter 31: Animal Origins and Lophotrochozoans Protostomes and Deutero- stomes: An Early Lineage Split Protostomes split into two major classes— lophotrochozoans and ecdysozoans.Protostomes split into two major classes— lophotrochozoans and ecdysozoans. Review Figure 31.14 31.14 28

29. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.14 figure 31-14.jpg

30. Chapter 31: Animal Origins and Lophotrochozoans Simple Lophotrochozoans Flatworms have no body cavity, lack organs for oxygen transport, have one gut entrance, and move via cilia.Flatworms have no body cavity, lack organs for oxygen transport, have one gut entrance, and move via cilia. Many species are parasitic. Many species are parasitic. Review Figures 31.15, 31.16 31.1531.1631.1531.1630

31. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.15 figure 31-15.jpg

32. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.16 figure 31-16.jpg

33. Chapter 31: Animal Origins and Lophotrochozoans Simple Lophotrochozoans No larger than many ciliated protists, rotifers have highly developed internal organs.No larger than many ciliated protists, rotifers have highly developed internal organs. Review Figure 31.17 31.17 33

34. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.17 figure 31-17.jpg

35. Chapter 31: Animal Origins and Lophotrochozoans Lophophorates: An Ancient Body Plan The lophotrochozoan lineage split into two branches, the lophophorates and the spiralians.The lophotrochozoan lineage split into two branches, the lophophorates and the spiralians.35

36. Chapter 31: Animal Origins and Lophotrochozoans Lophophorates: An Ancient Body Plan The lophophore dominates the anatomy of many lophophorate animals.The lophophore dominates the anatomy of many lophophorate animals. Review Figure 31.18 31.18 36

37. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.18 figure 31-18.jpg

38. Chapter 31: Animal Origins and Lophotrochozoans Lophophorates: An Ancient Body Plan Bryozoans are colonial lophophorates that can move their lophophores.Bryozoans are colonial lophophorates that can move their lophophores. Review Figure 31.20 31.20 38

39. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.20 figure 31-20.jpg

40. Chapter 31: Animal Origins and Lophotrochozoans Lophophorates: An Ancient Body Plan Brachiopods were much more abundant in the past than they are today.Brachiopods were much more abundant in the past than they are today.40

41. Chapter 31: Animal Origins and Lophotrochozoans Spiralians: Wormlike Body Plans The spiralian lineage gave rise to many phyla, most of whose members have wormlike body forms.The spiralian lineage gave rise to many phyla, most of whose members have wormlike body forms.41

42. Chapter 31: Animal Origins and Lophotrochozoans Spiralians: Wormlike Body Plans Ribbon worms have a complete digestive tract and capture prey with a reversible proboscis.Ribbon worms have a complete digestive tract and capture prey with a reversible proboscis. Review Figure 31.22 31.22 42

43. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.22 figure 31-22.jpg

44. Chapter 31: Animal Origins and Lophotrochozoans Segmented Bodies: Improved Locomotion Annelids are a diverse group of segmented worms that live in marine, freshwater, and terrestrial environments.Annelids are a diverse group of segmented worms that live in marine, freshwater, and terrestrial environments. Review Figure 31.23 31.23 44

45. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.23 figure 31-23.jpg

46. Chapter 31: Animal Origins and Lophotrochozoans Segmented Bodies: Improved Locomotion Mollusks evolved from segmented ancestors.Mollusks evolved from segmented ancestors. The three basic components of the molluscan body plan are the foot, mantle, and visceral mass.The three basic components of the molluscan body plan are the foot, mantle, and visceral mass. Review Figure 31.25 31.25 46

47. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.25 – Part 1 figure 31-25a.jpg

48. Chapter 31: Animal Origins and Lophotrochozoans Figure 31.25 – Part 2 figure 31-25b.jpg

49. Chapter 31: Animal Origins and Lophotrochozoans Segmented Bodies: Improved Locomotion The molluscan body plan yields a diverse array of animals that superficially appear very different from one another.The molluscan body plan yields a diverse array of animals that superficially appear very different from one another.49