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Success of Teleosts

Success of Teleosts. Success of Teleosts. Teleosts - ? Success - ?. Biogeography. Teleosts:. hagfishes placoderms acanthodians sturgeons bowfin teleosts. lampreys Chondrichthyes Sarcopterygii gars. Success of Teleosts. Success - ?

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Success of Teleosts

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  1. Success of Teleosts

  2. Success of Teleosts • Teleosts - ? • Success - ?

  3. Biogeography • Teleosts: hagfishes placoderms acanthodians sturgeons bowfin teleosts lampreys Chondrichthyes Sarcopterygii gars

  4. Success of Teleosts • Success - ? • Numbers of species = diversity - ca. 29,000 species (of 32,000 fishes) • More than all other groups of vertebrates combined (26,750)

  5. Success of Teleosts • Success - ? • Numbers of species - ca. ca. 29,000 species (of 32,000 fishes) -> Ostariophysi (most freshwater fishes) -> Perciformes and close relatives (most marine fishes)

  6. Success of Teleosts • Success - ? • Numbers of species • Numbers of individuals (as in Homo sapiens)

  7. Success of Teleosts • Success - ? • Numbers of species • Numbers of individuals • Longevity of species

  8. Success of Teleosts • Success - ? • Numbers of species • Numbers of individuals • Longevity - no (non-teleosts would win; specifically, living hagfishes, lampreys, sarcopterygians)

  9. Success of Teleosts • Success - ? • Numbers of species • Numbers of individuals • Dominance of marine and freshwater environments

  10. Success of Teleosts • Success - ? • Numbers of species • Numbers of individuals • Dominance of marine and freshwater environments Teleosts are common to abundant in all aquatic environments and exert major influence

  11. Success of Teleosts Factors: Size Maneuverability Protrusible premaxillae Nervous system/sociality

  12. Success of Teleosts • Size • Range in length from ca. 1/2 inch to 15 feet, but most are few inches. Average is probably less than 6 inches.

  13. Success of Teleosts • Size • Range in length from ca. 1/2 inch to 15 feet, but most are few inches. Average is probably less than 6 inches. • Much smaller than other fishes. E.g., sharks and rays average 3-6 feet. 0.5 ft 3.0 ft 12.0 ft

  14. Success of Teleosts • Size • Advantages of being small:

  15. Success of Teleosts • Size • Advantages of being small: a. Smaller generation time -- many teleosts reproduce at one year of age.

  16. Success of Teleosts • Size • Advantages of being small: a. Smaller generation time -> More predictably guarantees replacement.

  17. Success of Teleosts • Size • Advantages of being small: b. More habitats are available to small species E.g. crevices and holes in coral reefs, shallow rocky riffles

  18. Success of Teleosts • Size • Advantages of being small: b. More habitats are available to small species A small fish can live anywhere a large fish can live, but not vice versa.

  19. Success of Teleosts • Size • Advantages of being small: c. More types of food available to small species

  20. Success of Teleosts • Size • Advantages of being small: c. More types of food available to small species - as reflected in food pyramids. Top predators-> Autotrophs ->

  21. Success of Teleosts • Size • Advantages of being small: c. More types of food available to small species Many teleosts but few other fishes feed on plankton and other small organisms.

  22. Success of Teleosts • Size • Also are advantages in being large, especially escaping predation - more predators can feed on small fishes

  23. Success of Teleosts • Size • Also are advantages in being large, especially escaping predation But finding food and habitat space become more difficult as body size increases - > favoring small body size.

  24. Success of Teleosts • Size • Is there a lower limit to size?? Smallest fish = Paedocypris progenetica Cyprinid in Sumatra Sexually mature at 7.9 mm 1/3 inch

  25. Success of Teleosts • Size • Is there a lower limit to size?? Smallest fish = Paedocypris progenetica?? Male anglerfish sexually mature at 7.0 mm?

  26. Success of Teleosts • Size • Is there a lower limit to body size?? • Determined • By egg size? • By maneuverability? • By organ size? Is there a lower limit?

  27. Success of Teleosts • Size • Is there a lower limit to size?? • Determined • By egg size? • By maneuverability? • By organ size? Is there a lower limit? - ??

  28. Success of Teleosts 2.Maneuverability • Generally better developed in teleosts than in other fishes because they have: a. Gas bladder b. Lighter scales c. Improved position of paired fins

  29. Success of Teleosts 2.Maneuverability • a. Gas bladder keeps fishes at a nearly weightless state in water. Buoyancy equals gravitational pull.

  30. Success of Teleosts 2.Maneuverability • a. Gas bladder keeps fishes at a nearly weightless state in water. Buoyancy equals gravitational pull. Most teleosts have a gas bladder (secondarily lost in some). Elasmobranchs lack a gas bladder, must exert energy to maneuver.

  31. Success of Teleosts 2.Maneuverability • a. Gas bladder keeps fishes at a nearly weightless state in water. Buoyancy equals gravitational pull. Most teleosts have a physoclistous gas bladder (vs. physostomous gas bladder which has connection to gut and requires atmospheric air to fill).

  32. Success of Teleosts 2.Maneuverability • b. Lighter scales: Teleosts have shed the heavy armor and scales of earlier fishes (e.g., ganoid scales of gars, armor of placoderms). Lost the anti-predator advantages of armor but gained advantages associated with enhanced maneuverability.

  33. Success of Teleosts 2.Maneuverability • c. Position of paired fins. • Pelvic fins are far forward, being thoracic or jugular in position • Pectoral fins high on body --> Paired fins are located near center of gravity of fish.

  34. Success of Teleosts 2.Maneuverability • c. Position of paired fins. Pectoral and pelvic fins are used as pivots or brakes, enabling quick turning, stopping etc.

  35. Success of Teleosts 3. Protrusible premaxillae More advanced teleosts, including perciforms, have protrusible premaxillae (bones at the front of the upper jaw), meaning that they are capable of being extended forward from the front of the mouth.

  36. Success of Teleosts 3. Protrusible premaxillae -> Food can be approached more rapidly than is possible by swimming to it.

  37. Success of Teleosts 3. Protrusible premaxillae -> Also enables easier extraction from among bottom materials or from crevices.

  38. Success of Teleosts 3. Protrusible premaxillae -> Most importantly, condition has made possible the extreme diversification in the mouths and food habits of teleosts.

  39. Success of Teleosts 3. Protrusible premaxillae -> Most importantly, condition has made possible the extreme diversification in the food habits of teleosts. Most other fishes are carnivores (i.e., piscivores); teleosts are herbivores, insectivores, scale eaters, fin eaters, etc., as well as piscivores.

  40. Success of Teleosts Nervous system/sociality Sharks/rays appear to rely mainly on the lateral line and on olfaction to receive external information and react in very stereotypic ways.

  41. Success of Teleosts Nervous system/sociality Sharks/rays appear to rely mainly on the lateral line and on olfaction to receive external information and react in very stereotypic ways. Teleosts show much more plasticity in their reactions.

  42. Success of Teleosts Nervous system/sociality Teleosts show much more plasticity in their reactions. in orientation, sexual, and social behavior. Teleosts communicate with one another through fin movements, changes in color, body postures and sounds. They school. Some communicate interspecifically - e.g., symbiots, nest associates.

  43. Success of Teleosts Nervous system/sociality Teleosts show much more plasticity in their reactions. Evolution in teleosts parallels (to some degree) that of tetrapods; birds and mammals have more complex social behaviors than do amphibians.

  44. Success of Teleosts Nervous system/sociality Teleosts: Evolution of intelligence?

  45. Success of Teleosts Nervous system/sociality Teleosts: Evolution of intelligence? cf. Gars, minnows, cichlids.

  46. Success of Teleosts These 4 factors are observable trends. And I have presented them as causes for the success of teleosts. But, are they causal?

  47. Success of Teleosts These 4 factors are observable trends. But, are they causal? Correlations (positive or negative) can represent causal factors (evolutionary trend = success), but they can also simply be correlated with another factor that is causal.

  48. Success of Teleosts Are all 4 factors causal trends? Size -> <- Another factor = a function of size (or v.v.)

  49. Success of Teleosts

  50. Success of Teleosts Future?

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