1. MSC Biology of Fishes at NEAq

3. Week 3: B. Classes of Fishes Lamprey Chondrichthyes Osteichthyes

4. 3 classes of vertebrates = jawless, cartilaginous, bony

5. Class Chondrichthyes = “cartilaginous fishes” Week 3 vertebrae skeleton cartilage no bone jaws paired fins

6. Distinguishing CharactersProcesses skeleton fins fin rays scales jaws teeth heart intestine respiration regulation sensory reception reproduction

7. skeleton

8. fins

9. ceratotrichia fin rays dermal origin branching, segmentation no branching, no segmentation lepidotrichia epidermal origin

10. s/b ceratotrichia text error in 5 th edition (p. 257) bonus point

11. PLACOID scales enamel/dentine enamel/bone = teeth

12. dermal Figure 2.3 epidermal and dermal

13. Speedo Fastskin designed by 10x Olympic medalist Gary Hall, Jr placoid scales

14. jaws and teeth tiger shark

15. Chondrichthyes jaw loosely connected

17. Jaw

19. teeth Chondrichthyes embedded, replaced

20. serially replaced ~30,000 teeth avg./life modified scales

21. great white Carcharodon carcharius tooth height ~ body length

22. Carcharodon C. megalodonC. carcharius megatooth great white ~6 cm ~17 cm

23. 1:100 ratio tooth enamel height (cm) ≈ total body length (m) megatooth shark Miocene 16 to 1.6 MYA

24. jaw reconstruction of extinct megatooth shark Carcharadon megalodon 1909 (3x too large) recent SI estimate

25. Carcharodon megalodon mechanical megatooth “Bruce” Amityville, New England by Peter Benchley, 1974

26. heart pericardium:rigidsoft

27. intestine

29. Distinguishing CharactersProcesses skeleton fins fin rays scales jaws teeth heart intestine respiration regulation sensory reception reproduction

30. Respiration spiracles eyes electroreceptors nares 5 gill slits (6, 7)

31. great white shark gill arch ~ gill slit

32. ram ventilation

33. Regulation: ions retain nitrogen waste = [seawater]

34. OsteichthyesChondrichthyesBirds Nitrogen waste:

35. lipid-filled liver 1/3 of body wt 90% oil = buoyancy at any pressure = food reserve Regulation: buoyancy

36. Sensory Systems spiracles eyes electroreceptors nares 5 gill slits (6, 7)

37. photoreception tapetum lucidum (choroid layer) color vision lens muscles

38. chemoreception 1 drop of blood in Olympic-size pool most sensitive to proteins

39. mechanoreception low frequency sounds

40. electroreception Stefano Lorenzini Italy, 1678 AC muscle DC wounding

41. perpendicular forces

42. sexually dimorphic male female Reproduction cloaca anal and urogenital opening

43. myxopterygia

44. internal fertilization

45. embryo development external internal nutrient sources yolk placenta eggs embryos no larval stage

46. oviparity eggs develop external ~40%

47. “live” ovoviviparity eggs develop internal

48. viviparity young develops internal

49. life history strategy large size long life late maturity infrequent mating long gestation few large young