Vertebrate Diversity I

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Vertebrate Diversity I
2011-12-09 17:12:36
Vertebrate Diversity

Vertebrate Diversity I
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  1. What is Meant by ‘Chordate’?
    • Chordate does not = vertebrate
    • Chordate includes vertebrates and groups with similar evolutionary development
    • All chordates share several structural features
    • Chordates do not necessarily have a
    • backbone or bony skeleton!

  2. Features of Chordates
    • All chordates have four distinct
    • structures
    • Notochord a stiff flexible rod extending the length of the body
    • dorsal, hollow nerve cord lies above the digestive tract and expands to form the brain
    • Pharyngeal gill slits may form respiratory organs or may appear as grooves
    • post-anal tail which extends past the anus

  3. Humans as Chordates
    • In humans, the chordate features are best seen during embryonic development later, we lose our notochord, gill
    • slits, and tails
    • Only the dorsal nerve cord is retained in post embryonic human development

  4. Lancelets
    • Marine filter-feeders
    • Small, fishlike, invertebrate chordates
    • Retain all the four chordate features as adults
    • Live half-buried in the sand
    • Food particles are drawn into the mouth by pharyngeal cilia and are then transported to the digestive tract

  5. Tunicates:

    • Tunicates include sea squirts and salps
    • Marine
    • Larvae are motile and exhibit all key chordate features
    • Adult sea squirts are sessile filter-feeders that have lost their tail and notochord
    • Salps are not sessile
    • Live in the open ocean
    • Can be colonial

  6. Craniates
    • Craniates have a skull or braincase that encloses a brain
    • Includes hagfish (jawless fishes)
    • Includes vertebrates
    • the embryonic notochord is replaced
    • during development by a backbone, or vertebral column, composed of bone or cartilage

  7. Hagfish
    • Lack jaws
    • exclusively marine, and live near the ocean floor
    • They feed primarily on worms
    • They secrete massive quantities of slime as a defense against predators
    • Ectotherms
    • Lack a true vertebral column
    • Cartilage braincase (no bony skull)

  8. Vertebrates
    • Lampreys
    • Cartilaginous fishes (sharks, rays)
    • Ray-finned fishes
    • Coelacanths
    • Lungfishes
    • Amphibians
    • Reptiles
    • Mammals

  9. Characteristics of Vertebrates
    • Jaws allow vertebrates to exploit a much wider range of food sources
    • Paired appendages (fins, legs, wings) helped to stabilize movement
    • Complexity of the brain and sensory ability
    • Permits better perception of environment
    • Rapid response to stimuli
    • Internal skeleton
    • grow and repair itself
    • allowed for greater size and mobility,
    • enabling vertebrates to occupy most habitats

  10. Vertebrate Development
    • Patterns of embryonic development
    • are very similar for all vertebrates
    • All vertebrates are deuterostomes

  11. Vertebrates: Lampreys
    • Some lampreys parasitize fish
    • Like hagfishes, lampreys are jawless
    • Have a large rounded sucker that surrounds the mouth
    • Spinal cord is protected by cartilaginous segments
    • They live in both fresh and salt waters
    • Marine forms must return to fresh water to spawn
    • Invasive in Great Lakes

  12. Vertebrates: Cartilaginous Fishes
    • Chondrichthyes includes sharks, skates, and rays
    • Most are marine
    • Possess jaws and a cartilaginous skeleton
    • Body protected by a leathery skin embedded with tiny scales
    • They respire using gills

  13. Cartilaginous Fishes
    • Internal fertilization- male deposits sperm directly into a female’s reproductive tract (unlike other fish)
    • They tend to sink when they stop swimming because they lack a swim bladder
    • Many are filter feeders, most predators
    • Specialized sensory organs
    • Can be benthic (seafloor living) or pelagic (open ocean)
  14. Vertebrates: Ray-finned

    • Diverse clade
    • Freshwater and marine
    • Bony skeletons
    • Interlocking scales on skin
    • Gills
    • Swim bladder

  15. Vertebrates: Lobe-finned fishes
    • Lungfish and coelacanths
    • Share common ancestor with tetrapods (Tiktaalik)
    • Lungfish have lungs and gills
    • Freshwater, can survive low oxygen and without water!
    • Coelacanths
    • Thought to be extinct until 1938