The Fishes: Vertebrate Success in Water

1. The Fishes:Vertebrate Success in Water The Fishes:Vertebrate Success in Water Chapter 18 Chapter 3 By Anna Maria Noronha

2. Fish vs. Fishes “The ocean is full of fishes.” “This tank is full of fish.”

3. Phylum Chordata- notochord, pharyngeal slits, dorsal tubular nerve cord, postanal tail. • Group Craniata: skull surrounds brain, olfactory organs, eyes, and inner • Subphylum Hyperotreti- fishlike; skull cartilaginous bars; jawless; slime glands; Hagfish • Subphylum Vertebrata- vertebrate surrounds nerve cord

4. Evolutionary Evidence • Hagfish are the most primitive living craniates. • 2 Key craniate characteristics is: the brain and bone • 530 million years ago possible fossil with brain • 500 million years ago bone well developed in group of fishes called Ostracoderms (bony armor) The first vertebrates were fishlike animals that appeared more than 500 million years ago. The internal skeletons of these jawless creatures were cartilaginous and rarely preserved. Ostracoderms had bony external shields that covered the head and most of the trunk.

5. Evolutionary Evidence • First vertebrates probably marine • Vertebrates did adapt to freshwater and much of the evolution of fish occurred there. • Early vertebrate evolution involved the movement of fishes back and forth between marine and freshwater environments.

6. Evolutionary Evidence The importance of freshwater in the evolution of fishes is evidenced by the fact that over 41% of all fish species are found in freshwater, even though freshwater habitats represent only a small percentage (0.0093% by volume) of the earth’s water resources.

7. Subphylum Hyperotreti The Hagfish • Head-supported by cartilaginous bars • Brain- enclosed in fibrous sheath Intro video to Hagfish

8. Subphylum Hyperotreti • Lack vertebrae • Retain notochord (axial supportive structure) • 4 pairs of sensory tentacles surrounding their mouths • Ventrolateral slime glands See the copious amounts of slime See hagfish make a knot

9. Subphylum Hyperotreti • Found: cold water marine habitats • Feed on: soft bodied invertebrates or scavenge on dead or dying fish • To provide leverage, the hagfish ties a knot in its tail and passes it forward to press against the prey Eating on dead whale carcass

10. Subphylum Vertebrata • Vertebrae that surrounds a nerve cord and serves as the primary axial support • Most are vertebrates are members of the superclass Gnathostomata • Jawed fishes • Tetrapods

11. Ostracoderms • Extinct agnathans (without jaws) that belong to several classes. • Bottom dwellers and very sluggish • Filter feeders • Bony armor • Bony plates around mouth to act like a jaw

12. Class Cephalaspidomorphi • Cephala-head, aspidos- shield, morphe-form Lampreys -agnathans

13. Class Cephalaspidomorphi • Live in both marine and freshwater • Larva filter feeders • Adults prey on fish • Mouth –suckerlike with lips for attachment functions

14. Class Cephalaspidomorphi • Attach to prey with lips and teeth • Use tongues to rasp away scales

15. Class Cephalaspidomorphi • Salivary glands with anticoagulant; feed on blood

16. Class Cephalaspidomorphi • Two types: • Freshwater brook lampreys • Freshwater • Larval stage can last three years • Adults only reproduce, never leave stream, then die

17. Class Cephalaspidomorphi • Two types: • Sea lamprey • Live in ocean or Great lakes • End of live, migrate to freshwater stream to spawn • Female attaches to a stone with mouth • Male uses his mouth and attaches to female’s head • Eggs are shed • Fertilization is external

18. Sea lamprey Reproduction:

19. Gnathostomata Vertebrates with jaws (evolved from anterior pair of pharyngeal arches) • Jaws importance: • More efficient gill ventilation • Capture and ingestion of a variety of food sources

20. Gnathostomata • Paired appendages importance: • Decease rolling during locomation • Controls tilt or pitch • Lateral steering

21. Body parts of fish Get ready to draw a fish!!!

22. 1. Caudal fin - tail fin Used for forward motion and acceleration

23. 2. Dorsal fin & 3. Anal fin Singular fins Used to prevent rolling/tipping

24. 4. Pectoral fin & 5. Pelvic fin Paired fins (left & right) Used to balance, stop & turn

25. 6. Spines Used for protection Some contain poison sacs

26. 7. Operculum Covers & protects gills Not found in sharks

27. 8. Lateral line Sensory canals used to detect changes in water pressure around the fish (similar to human ear)

28. Gnathostomata • Jaws and appendages: • Increase predatory lifestyles • More feeding: • Increase offspring • Exploit new habitats

29. Gnathostomata • Two Classes: • Class Chondrichthyes- sharks, skates, rays, ratfish • Class Osteichthyes- bone fish

31. Class Chondrichthyes Chondro- cartilage, ichthyes- fish • Sharks, skates, rays, ratfish • Carnivores or scavengers • Most marine

32. Order : pluerotremata • Body typically spindle shaped. • Gill slits lateral • Tail heteroceral • Ex: Dog fishes, sevengilled shark, zebra shark, whale shark, hammer headed shark.

34. Order 2 : Hypotremata • Body depressed , flattened dorsoventrally , • Gill slits ventral, 5 pairs, • Pectoral fin enlarged / fuced to sides of head. • Ex: skates ,rays , saw fish

36. Skates and rays Life on the ocean floor in shallow waters Wing like appendages Camouflage The little skate settles on the ocean floor where it blends in with the light colored sand. It can easily surprise any prey while waiting in this position.

37. Class Chondrichthyes • Biting mouthparts • Paired appendages • Placoid scales (gives skin tough, sandpaper texture) • Cartilaginous endoskeleton These sharply pointed placoid scales are also known as dermal teeth or denticles. They give the shark’s skin the feel of sandpaper. The tip of each scale is made of dentine overlayed with dental enamel. The lower part of each scale is made of bone. The scales disrupt turbulence over the skin, considerably reducing the drag on the shark as it swims.

38. Class Chondrichthyes Subclass Elasmobranchii elasmos- plate metal, branchia- gills Sharks, skates, rays 820 species Placoid scales

39. Subclass Elasmobranchii • Shark teeth are modified placoid scales • Rows of teeth • As outer teeth wear out, newer teeth move into position from inside jaw and replaces them How many teeth do sharks have?

40. Subclass Elasmobranchii • Largest living sharks? • Filter feeders- whale shark • Pharyngeal-arch modifications that strain plankton

41. Subclass Elasmobranchii • Fiercest most feared sharks? • Great white shark Great White Shark (Carcharodon carcharias),South Africa, Atlantic Ocean.

42. Subclass Holocephali Holo- whole, cephal-head • Ratfish • Lack scales • Gill covered with operculum • Teeth large plates for crushing

43. Class Osteichthyes • Osteo- bone, ichthyes- fish • Bone in skeleton and/or scales • Bony operculum covering the gill openings • Lungs or swim bladder

44. Class Osteichthyes • Subclass Sarcopterygii Sacro-flesh, pteryx- fin • Muscular lobes associated with fins • Use lungs in gas exchange

45. Subclass Sarcopterygii order : Dipnoi Lungfish • Live in regions where seasonal droughts are common • When water stagnates and dry up use lungs to breathe air • Air bladder paired lung like

46. Subclass Sarcopterygiiorder : crossopterygii Coelacanths • Thought to be exinct • But 1938 in South Africa, found one • In 1977 another species found off coast of Indonesia • Caudal fin 3 lobed • Pre maxillae ,maxillae present • Air bladder vistigial A coelacanth swimming near Sulawesi, Indonesia

47. Subclass Sarcopterygii Osteolepiforms • Are extinct • Believe to be ancestors of ancient amphibians

48. Subclass Actinopterygii • Actin- ray, pteryx-fin • Ray-finned fishes because their fins lack muscular lobes • Swim bladder-gas-filled sacs along the dorsal wall of the body cavity that regulates buoyancy Swim_bladder of a Rudd (Scardinius erythrophthalmus)

49. Subclass Actinopterygii • One group is called: Chondrosteans • 25 living species today • Ancestral species had a bony skeleton but living members have a cartilaginous skeleton. • Tail with a large upper lobe.

50. Subclass Actinopterygii Chondrosteans • Sturgeons • Live in sea and migrate into rivers to breed • Bony plates cover the anterior of body • Valued for their eggs-caviar (severely overfished)