The Animal Kingdom: The Deuterostomes

1. The Animal Kingdom:The Deuterostomes Chapter 31

2. Learning Objective 1 • What are the shared derived characters of deuterostomes?

3. Deuterostomes1 • Include echinoderms, hemichordates, chordates • Hemichordates (acorn worms) • marine deuterostomes • three-part body (proboscis, collar, trunk)

4. Deuterostomes2 • Shared derived characters • radial, indeterminate cleavage • blastopore becomes anus • larva have a loop-shaped ciliated band used for locomotion

5. KEY CONCEPTS • The echinoderms and the chordates are the two most successful deuterostome lineages in terms of diversity, number of species, and number of individuals

6. Learning Objective 2 • What are three shared derived characters of echinoderms? • Describe the main classes of echinoderms

7. PhylumEchinodermata • Marine animals with • spiny “skin” • water vascular system • tube feet • endoskeleton • Larvae exhibit bilateral symmetry • Most adults exhibit pentaradial symmetry

8. Sea Star Body Plan

9. Stomach Digestive gland Tube feet Anus Ampulla Spine Gonad Dermal gill Pedicellariae Fig. 31-2a, p. 670

10. ClassCrinoidea • Sea lilies, feather stars • oral surface turned upward • some crinoids are sessile

11. ClassAsteroidea • Sea stars • central disc with five or more arms • use tube feet for locomotion

12. ClassOphiuroidea • Brittle stars • arms longer, more slender than sea stars • arms more distinct from central disc • use arms for locomotion • tube feet lack suckers

13. ClassEchinoidea • Sea urchins, sand dollars • lack arms • have a solid shell • are covered with spines

14. ClassHolothuroidea • Sea cucumbers • elongated flexible bodies • circle of modified tube feet surrounds mouth

15. Fig. 31-1, p. 669

16. KEY CONCEPTS • Echinoderms are characterized by radial symmetry in adults, a water vascular system, tube feet, and spiny skin

17. Learning Objective 3 • What are five shared derived characters of chordates?

18. PhylumChordata 1 • Subphylum Urochordata • Subphylum Cephalochordata • Subphylum Vertebrata

19. Chordate Evolution

20. PhylumChordata 2 • At some time during life cycle have • flexible, supporting notochord • dorsal, tubular nerve cord • pharyngeal (gill) slits • muscular postanal tail • endostyle (or thyroid gland)

21. Chordate Body Plan

22. Dorsal, tubular nerve cord Brain Postanal tail Notochord Mouth Pharynx Anus Pharyngeal (gill) slits Muscular segments Intestine Heart Fig. 31-4, p. 671

23. KEY CONCEPTS • At some time in its life, a chordate has a notochord; dorsal, tubular nerve cord; pharyngeal slits; and a muscular postanal tail

24. Learning Objective 4 • What are the invertebrate chordate subphyla?

25. SubphylumUrochordata • Tunicates • marine animals with tunics • suspension-feeders • Larvae are free swimming • Most adults are sessile

26. Tunicate Body Plan

27. Chordata Cephalochordata (lancelets) Echinodermata (sea stars, sea urchins) Hemichordata (acorn worms) Urochordata (tunicates) Vertebrata Deuterostome ancestor Fig. 31-5a, p. 672

28. Incurrent siphon Ganglion Oral tentacles Excurrent siphon Pharynx with slits Atrium Endostyle Tunic Intestine Esophagus Testis Digestive gland Ovary Stomach Heart Fig. 31-5b, p. 672

29. 0.5 mm Fig. 31-5c, p. 672

30. Incurrent opening Pharynx with slits Atrium Excurrent opening Nerve cord Adhesive papilla Notochord Heart Stomach Fig. 31-5d, p. 672

31. SubphylumCephalochordata • Lancelets • small, segmented, fishlike animals

32. Chordata Echinodermata (sea stars, sea urchins) Cephalochordata (lancelets) Hemichordata (acorn worms) Urochordata (tunicates) Vertebrata Deuterostome ancestor Fig. 31-6 (1), p. 673

33. Tentacles Nerve cord Pharyngeal slits Notochord Caudal fin Intestine Tentacles Endostyle Atrium Gonads Atriopore Anus Fig. 31-6 (a-b), p. 673

34. Learn more about the body plans of the deuterostomes by clicking on the figures in ThomsonNOW.

35. Learning Objective 5 • Discuss the evolution of chordates

36. Evolution ofChordates • Urochordates (tunicates) • probably first chordates to evolve • Subphyla Cephalochordata and Vertebrata • sister taxa (recent common ancestor)

37. Vertebrate Evolution

38. Explore the evolutionary relationships of vertebrates by clicking on the figure in ThomsonNOW.

39. Learning Objective 6 • What are four shared derived characters of vertebrates?

40. Vertebrates 1 • Vertebral column • chief skeletal axis of body • Cranium • braincase • Neural crest cells • determine development of many structures

41. Vertebrates 2 • Pronounced cephalization • Complex brain • Muscles attached to endoskeleton for movement

42. KEY CONCEPTS • Shared derived characters of vertebrates include a vertebral column, cranium, neural crest cells, and an endoskeleton of cartilage or bone

43. Learning Objective 7 • What is the difference between the major groups of jawless fishes?

44. Jawless Fishes 1 • Ostracoderms (extinct) • among earliest known vertebrates • Agnathans (hagfishes) • class Myxini • Lampreys • class Cephalaspidomorphi

45. Hagfish

46. Lampreys

47. Hagfishes • Have no trace of vertebrae • Why are they classified as vertebrates? • Some systematists classify vertebrates plus hagfishes as craniates (Craniata) • But molecular data support classifying hagfishes as vertebrates

48. Jawless Fishes 2 • Jaws and paired fins absent • in both hagfishes and lampreys • Hagfishes • marine scavengers • secrete slime as a defense mechanism • Lampreys • many are parasites on other fishes

49. Learning Objective 8 • Trace the evolution of jawed fishes and early tetrapods • Identify major taxa of jawed fishes and amphibians

50. Class Chondrichthyes (Cartilaginous Fishes) • Includes sharks, rays, skates • Cartilaginous fishes have • jaws • two pairs of fins • placoid scales