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Lancelet, Branchiostoma

Lancelet, Branchiostoma. Outline. Chordates Non-vertebrate Chordates Vertebrates Fishes Amphibians Reptiles Birds Mammals. Chordates. Phylum Chordata Four Main Characteristics Notochord Nerve Cord Pharyngeal Pouches Tail. Invertebrate Chordates.

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Lancelet, Branchiostoma

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  1. The Vertebrates

  2. Lancelet, Branchiostoma

  3. Outline • Chordates • Non-vertebrate Chordates • Vertebrates • Fishes • Amphibians • Reptiles • Birds • Mammals

  4. Chordates • Phylum Chordata • Four Main Characteristics • Notochord • Nerve Cord • Pharyngeal Pouches • Tail

  5. Invertebrate Chordates • Notochord persists and is never replaced by a vertebral column • Lancets (Subphylum Cephalochordata) • Sea Squirts (Subphylum Urochordata)

  6. Sea squirt, Halocynthia

  7. Vertebrates • Subphylum Vertebrata • Internal jointed skeleton of vertebrates is living tissue that grows with the animal • Main axis of skeleton consists of vertebral columns and a skull that encloses the brain • Cephalization is accompanied by sense organs • Evolution of jaws and predation • Amnion allows reproduction on land

  8. Phylogenetic Tree of the Chordates

  9. Vertebrate Features • Living endoskeleton with vertebral column • Closed circulatory system • Paired appendages • Efficient respiration and excretion • High degree of cephalization • Adapted to active lifestyles

  10. Fishes • Fishes: • Aquatic, gill-breathing vertebrates • Usually have fins and scale-covered skin • Jawless fishes (Superclass Agnatha) • Ostracoderms - earliest vertebrate fossils • Lampreys and hagfishes are modern-day jawless fishes that lack a bony skeleton

  11. Lamprey, Petromyzon

  12. Fishes With Jaws • Gnathostomates have jaws • Jaws thought to have evolved from first pair of gill arches of agnathans • Placoderms • Extinct jawed fishes of Devonian • Thought to be ancestral to sharks and bony fish

  13. Cartilaginous Fishes • Class Chondrichthyes have a skeleton of cartilage instead of bone • Cartilaginous Fishes • Sharks, rays, skates • Lack gill cover of bony fish • Utilize lateral line system • Filter feeders and predators • Pectoral fins can be enlarged into large, wing-like fins

  14. Cartilaginous fishes

  15. Bony Fishes • Class Osteichthyes have a skeleton of bone • Most are ray-finned fishes • Lobe-finned fishes are small subgroup with fleshy fins supported by central bones • Swim bladder • Gas-filled sac in bony fishes • Volume can be altered to change buoyancy

  16. Ray-finned Fishes

  17. Amphibians • Tetrapods (four limbs) • Hypotheses of tetrapod evolution • Lobe-finned fishes had an evolutionary advantage due to movement capability • further adaptations promoted by: • Supply of food on land, and • Absence of predators

  18. Lobe-finned Fish vs. Amphibian

  19. Diversity of Amphibians • Amphibians today occur in three groups: • Salamanders and newts • Salamanders practice internal fertilization • Frogs and toads • Tailless • Caecilians • Legless, sightless, worm-shaped • Most return to water for reproduction

  20. Amphibians

  21. Amphibian Features • Usually tetrapods • Lungs usually present in adults • Metamorphosis • Smooth and moist skin • Three-chambered heart • Ectothermic

  22. Metamorphosis

  23. Vertebrate Circulatory Pathways

  24. Reptiles • Class Reptilia • Thought to have evolved from amphibian ancestors by the Permian period • Practice internal fertilization • Lay eggs protected by a leathery shell (amniotic egg)

  25. Phylogenetic Tree of Reptiles

  26. Anatomy and Physiology of Reptiles • Reptiles have a thick, scaly skin that is keratinized and impermeable to water • Usually tetrapods • Lungs with expandable rib cage • Shelled amniotic egg • Dry, scaly skin • Ectothermic

  27. Reptilian Diversity

  28. Reptilian Anatomy

  29. Birds • Characteristics of Class Aves • Feathers • Hard-shelled amniotic egg • Four-chambered heart • Often winged • Air sacs • Endothermic

  30. Bird Anatomy and Flight

  31. Bird Beaks

  32. Mammals • Class Mammalia • Thought to have evolved during the Mesozoic Era from therapsids • Mammalian skull accommodates a larger brain relative to body size • Chief characteristics and hair and milk-producing mammary glands • Infant dependency • Internal development • Differentiated teeth

  33. Monotremes and Marsupials

  34. Mammals • Monotremes - Hard-shelled amniotic eggs • Marsupials - Females contain pouch • Placentals - Females have organ for exchange of maternal and placental blood

  35. Placental Mammals

  36. Perissodactyla Horses Artiodactyla Deer Carnivora Cats Primates Monkeys Cetacea Whales Chiroptera Bats Rodentia Mice Proboscidea Elephants Lagomorpha Rabbits Major Orders of Mammals

  37. Review • Chordates • Non-vertebrate Chordates • Vertebrates • Fishes • Amphibians • Retiles • Birds • Mammals

  38. The Vertebrates

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