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Chordata

Chordata. All vertebrates are chordates, but not all chordates are vertebrates. Traits – at some time in their lives. Dorsal notochord. In vertebrates, the notochord is replaced with a backbone. Traits. Dorsal nerve cord. Traits. Gill slits. Traits. Post anal tail. Prevertebrates.

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Chordata

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  1. Chordata • All vertebrates are chordates, but not all chordates are vertebrates

  2. Traits – at some time in their lives • Dorsal notochord In vertebrates, the notochord is replaced with a backbone

  3. Traits • Dorsal nerve cord

  4. Traits • Gill slits

  5. Traits • Post anal tail

  6. Prevertebrates • Chordates that never quite develop a backbone, shows an evolutionary link between invertebrates and vertebrates • E.g. – sea squirts, lancelets

  7. Sea squirts

  8. Lancelets

  9. Vertebrates • Animals with a backbone and skull

  10. Agnatha – “jawless fish” • E.g. – lampreys, hagfish, slime eels

  11. Chondrichthyes – “cartilage fish” • E.g. – sharks, rays, skates

  12. Osteichthyes – “bony fish” • E.g. – trout, carp, catfish, tuna

  13. Amphibia – frogs, salamanders

  14. Reptiles – snakes, lizards, crocodiles, turtles

  15. Aves – birds

  16. Mammalia – humans, cats, horses

  17. Advantages of the vertebrates • By having a backbone to protect the spinal cord and a skull to protect the brain, the nervous system can be better developed and can have higher intelligence

  18. Vertebrate behavior • Innate – born with it, not learned • Reflex – single automatic response to a single stimulus • Instinct – more complex response to a series of stimuli

  19. Instincts • Self preservation – save yourself E.g. – run away from danger

  20. Instincts • Species preservation – save species, pass on your genes E.g. – killdeer fake a broken wing to draw predators away from her nest

  21. Learned behavior • Requires memory, present behavior is influenced by past experiences

  22. Conditioned response • Behavior that is learned through repetition accompanied by rewards and punishments • E.g. – if you reward a dog for coming to your whistle, it will continue the behavior

  23. Higher intelligence • Communication, using tools, problem solving, curiosity, boredom, abstract thought, symbols

  24. Class Agnatha – “jawless fish” • E.g. – lamprey, hagfish, slime eels

  25. Traits • No jaws

  26. Traits • Cartilage skeleton

  27. Traits • Scaleless, mucousy skin

  28. Traits • 2 chambered heart

  29. Traits • 7-13 pairs of gill slits

  30. Traits • Ectotherms (cold blooded) – temp. varies with the environment

  31. Traits • Oviparous – lay eggs

  32. Traits • No paired fins

  33. Lampreys • Feed on fish by attaching with their mouths and rasping through the skin – got into the upper Great Lakes through a manmade canal

  34. Inject an anticoagulant to keep blood flowing – fish die from blood loss

  35. Lesson from problem • Before we alter the environment, we better consider all the possible consequences

  36. Lamprey life cycle • Adults live in lakes and feed on fish. Swim upriver to mate and lay eggs which hatch into larvae. They spend 2-7 years in mud filter feeding. Metamorphosize into small lamprey that go downstream into lakes, start over.

  37. Cure? • The best we can hope for is to keep the population as low as possible

  38. Hagfish • Feed on dead or dying fish by burrowing inside and eating from the inside out eyespots

  39. SLIME!!! – secrete slime to suffocate predators

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