Fishes

1. Fishes Bio II Rupp

2. Types of Fishes • Jawless • Cartilaginous • Bony

4. Fish Characteristics • 4 hallmarks of chordates • Sharks • Lateral line • Ampullae of Lorenzini • Operculum • Gills • Tail types • Scale types • Fish musculature • Swimming and the swim bladder

5. Taxonomy • Kingdom Animalia • Phylum Chordata • Subphylum Vertebrata

6. Hagfish Class Myxini

7. Lampreys Class Cephalospidomorphi

8. Sharks, skates, and rays Class Chondrichthyes

9. Ray-finned fishes Class Actinopterygii

10. Lobe-finned fishes Class Sarcopterygii

11. Chordate Hallmarks • Notochord • Hagfishes and lampreys keep this their entire lives • Made of thick-walled and fluid-filled cells pressed closely together

12. Chordate Hallmarks • Dorsal hollow nerve cord • Neural tube formation • Anterior becomes the brain

13. Chordate Hallmarks • Pharyngeal gill slits/pouches

14. Chordate Hallmarks

15. Fish Definition • For our purposes: • A gill-breathing, poikilothermic (cold-blooded), aquatic vertebrate that possesses fins and a skin that is usually covered in scales • Approximately 25,000 species • Two basic body forms • Agnathans—jawless • Gnathostomes—jawed

16. Agnathans • Cephalospidomorphi—lampreys—ectoparasites • Myxini—hagfishes—scavengers

21. SuperclassGnathostomes • Cartilaginous fishes • Class Chondrichthyes—approx. 850 species • Subclass Elasmobranchii—sharks, skates, and rays • Dogfish anatomy

22. Dogfish Anatomy

23. Dogfish Anatomy

24. Dogfish Anatomy

25. Gnathostome Adaptations

26. Gnathostome Adaptations

27. Gnathostome Reproductive Strategies • Internal fertilization • Oviparous—some species lay eggs immediately after fertilization • Ovoviviparous—retain the developing young in the uterus and they are nourished by yolk sacs • Viviparous—young are nourished by a placenta

28. SuperclassGnathostomes • Bony fishes, aka osteichthyes • Class Actinopterygii—ray-finned fishes • Class Sarcopterygii—lobe-finned fishes

29. Osteichthyes Adaptations • Operculum • Tail types • Skin and scales • Musculature • Swimming • Swim bladder • Gills

30. Operculum • A bony plate attached to a series of muscles running over the gills • Aid in more efficient respiration • Bernoulli’s Principle of Fluid Dynamics

32. Tail Types

33. Scale Types • Scales are embedded in the dermis and covered by the epidermis • Types • Ganoid • Cycloid • Ctenoid • Placoid

34. Ganoid scales

35. Cteniod scales

36. Cycloid scales

37. Typical in sharks Placoid scales

38. Fish Musculature • Myomeres-segments of the muscle • Myospeta—division point of the myomeres • Vertical septum and horizontal septum of body cavity

40. Fish Musculature • Red muscle or dark muscle is used in regular swimming • Red muscle is dark due to extra myoglobin and extreme vascularization • Red muscle is often referred to as the bloodline • White muscle for escape response

41. Swimming • Short muscular bodies and lunate tails for most efficient swimming

42. Swim bladders • Maintain neutral buoyancy and depth control • Balloon-like structure • Pulls gas out of the water to inflate • Two types • Attached to gut—ancient fishes • Detached from gut—more modern fishes • Fish without swim bladders: tuna, flounder, sharks, deep ocean fish • Sharks have a huge fatty liver to maintain neutral buoyancy

44. Gills • Made of filaments called lamellae • Rich with blood vessels • Covered by operculum or gill slits • Counter current blood flow of blood and water increases efficiency—demonstration • Gill arches are the point of attachment for lamellae • Gill rakers remove debris from gills • Larger gill surface is often correlated with higher fish activity levels