Vertebrate Diversity I The Protochordates Subphylum Vertebrata

1. Vertebrate Diversity IThe ProtochordatesSubphylum Vertebrata BIO 112

2. Q1: Deuterostomes • Have radial, indeterminate cleavage • Are ancestrally enterocoelous • Develop the mouth as the second gut opening • All of the above

3. Deuterostomes and Chordates • Generic deuterostome characteristics: • Radial, indeterminate cleavage • Enterocoely • Deuterostomy • The four Chordate characteristics: • Notochord • Pharyngeal gill slits • Post-anal tail • Dorsal hollow nerve chord (+ trends toward segmentation and cephalization)

4. The “Protochordates” • Ph. Hemichordata • Ph. Chordata • Subph. Urochordata • Subph. Cephalochordata

5. Q2: The only chordate character retainedby adult tunicates is the • Notochord • Pharyngeal gill slits • Dorsal hollow nerve chord • Post-anal tail

6. Q3: The closest protochordatevertebrate ancestors are the • Echinoderms • Hemichordates • Urochordates • Cephalochordates

7. Sub-ph. VertebrataCentral characteristics: • segmented vertebral column (i.e., backbone) • cranium (brain case: bone or cartilage) • closed circulatory system • neural crest cells • become teeth, part of cranium, adrenal glands • nephritic kidneys • semicircular vestibular canals • seconarily schizocoelous

8. Sub-ph. VertebrataBases for classification(shared derived traits) : cranium and jaws lateral appendages consolidation of vertebrae cartilagenous vs. bony skeleton tetrapody and petadactyly anamniotic vs. amniotic egg endothermy vs. ectothermy scales, feathers, fur milk extended parental care

9. Q4: Which of the following is NOTa distinguishing vertebrate character? • Neural crest cells • Nephritic kidneys • Radial symmetry • A segmented backbone

10. Class (or Superclass) Agnatha • Jawless fishes • circular mouths; specialized feeding • notochord persists through life • lack paired appendages • single dorsal nostril • 2 extant taxa: • Myxini: hagfish • Cephalaspidomorphi: lamprey

11. Ostracoderms: extinct agnathans

12. The lamprey -- an ectoparasite

13. Lamprey on prey

14. Lamprey mouth -- yikes!

15. Lamprey ammocoetes larva:(clear affinity with cephalochordates) A gravel-dwelling filter feeder when young

16. Hagfish -- a scavenger

17. This is why it’s called the “slime hag”!

18. Q6: “Agnathans” derive their namefrom their lack of • Paired nostrils • Jaws • Paired lateral appendages • A segmented backbone

19. Superclass Agnatha: Cl. Myxini Cl. Cephalaspidomorphi/ Petromyzontia Superclass Gnathostomata Cl. Chondrichthyes Cl. Osteichthyes C. Amphibia Cl. Reptilia Cl. Mammalia Cl. Aves Jaws or No Jaws?

20. The Placoderms: first jawed fishes (now extinct)

21. Evolution of Jaws from Gill Arches

22. Cl. Chondrichthyes • Cartilaginous fishes: sharks, skates, rays • light-weight, elastic skeleton • Gills • Paired fins (pectoral and pelvic fins) • Large oily liver for buoyancy • Heterocercal tail • Scavengers or predators

23. Sharks

24. Heterocercal tail

25. Shark jaws with choppers . . . If jaws evolved from gill arches, where did teeth come from?

26. Denticles on shark skin

27. Skates

28. Manta Ray (or, “BayWatch meets the Chondrichthyes”)

29. Cl. Osteichthyes • Bony fishes: about half of all vertebrates! • Gills with operculum: gill cover • Swim bladder for buoyancy • derived from outpocketing of pharynx • flexible pectoral fins • can provide propulsion (not in shark)

30. Q6: The Osteichthyes differ from the major Chondrichthyes groups in having • A swim bladder • A bony skeleton • Gill covers (opercula) • All of the above

31. Examples of bony fishes

32. Fish with swim bladder

33. Sub-Cl. Actinopterygii “ray-finned fish” actino = ray Very diverse: the majority of fish! Sub-Cl. Sarcopterygii “lobe-finned fish” sarco = flesh Only 4 genera, but very interesting, evolutionarily 2 Orders: Dipnoi, Crossopterygii 2 sub-classes of Bony fishes:

34. The dipnoans • Lung fish (also have gills . . . ) • “Dipnoan” = double breathing • Fresh water • 1 genus each in Africa, Australia, S. America

35. The Queensland Lung fish Australian speies

36. Order Crossopterygii • The only extant species is the Coelocanth • (Latimeria) • a living fossil known from 70 m.y. old fossils • Re-discovered in 1938 in W. Indian Ocean • the lobed fins evolved into the 4 limbs of the tetrapods” (terrestrial verts)

37. Can’t get enough of that Latimeria!

38. The “fishapod” – a likely transition from fish to amphibian Tiktaalik roseae – the “fishapod” ~ 380mya The muscular, bony, lobed fins were nicely pre-adapted for locomotion on land

40. Q7: The most successful and speciosegroup of bony fish are the • Chondrichthyes • Actinopterygii • Dipnoi • Crossopterygii

41. Q8: The bony fish most closelyrelated to our ancestors are the • Chondrichthyes • Actinopterygii • Dipnoi • Crossopterygii

42. Class Amphibia • Most return to water to reproduce; larvae often have gills • Amphi-bios = “double life” • need moist skin for gas exchange • small, inefficient lungs • fertilization usually external • are ectotherms

43. Class Amphibia • Order Urodela (salamanders) • Order Anura (toads, frogs) • Order Apoda (caecilians)

44. Q9: Why are amphibians called “amphibians”? • They all have smooth, thin skins • They all must return to the water to reproduce • They are all external fertilizers • They all have multiple larval forms

45. O. Urodela -- salamanders • Have Legs and tails (uro = “tail”) • May have lungs or be lungless • Terrestrial or aquatic Spotted salamander

46. Red-backed salamander

47. Red eft -- terrestrial stage

48. Hellbender -- huge aquatic sally!

49. O. Anura: frogs, toads • Tail-less (a + uro) • Jumpers or hoppers • aquatic larval stage (the tadpole) Leopard frog (Rana pipiens)

50. American Toad