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2013-04-03 12:47:23
Life 103

test 3
Show Answers:

  1. vertebrates are a subphylum inside of what phylum?
  2. what two groups of invertebrate deuterostomes are more closely related to vertebrates than invertebrates?
    urochordates and cephalochordates
  3. how did vertebrates get their name?
    get their name from vertebrae, the series of bones that make up the backbone
  4. Chordates
    are bilaterian animals that belong to the clade of animals known as Deuterostomia
  5. how many species in vertebrates and diversity
    • ~52,000 species of vertebrates, including the largest organisms ever to live on the Earth
    • Vertebrates have great diversity, a wide range of differences within the group
  6. Four key characters of chordates
    • Notochord
    • Dorsal, hollow nerve cord
    • Pharyngeal slits or clefts
    • Muscular, post-anal tail
    • Some species have some of these traits only during embryonic development
  7. Chordate
  8. Notochord
    • is a longitudinal, flexible rod between the digestive tube and nerve cord
    • support for organs
    • provides skeletal support throughout most of the length of a chordate
    • In most vertebrates, a more complex, jointed skeleton develops, and the adult retains only remnants of the embryonic notochord
  9. Nerve cord
    • of a chordate embryo develops from a plate of ectoderm that rolls into a tube dorsal to the notochord
    • The nerve cord develops into the central nervous system: the brain and the spinal cord
  10. Pharyngeal clefts
    • grooves in the pharynx 
    • develop into slits that open to the outside of the body
    • Functions of pharyngeal slits:
    • –Suspension-feeding structures in many invertebrate chordates
    • –Gas exchange in vertebrates (except vertebrates with limbs, the tetrapods)
    • –Develop into parts of the ear, head, and neck in tetrapods
  11. Tail
    • posterior to the anus
    • In many species, the tail is greatly reduced during embryonic development
    • The tail contains skeletal elements and muscles
    • It provides propelling force in many aquatic species
  12. chordate phylogeny
  13. lancelets
    • named for their bladelike shape
    • They are marine suspension feeders that retain characteristics of the chordate body plan as adults
  14. lancelet
  15. tunicate
  16. tunicates
    • are more closely related to other chordates than are lancelets
    • They are marine suspension feeders commonly called sea squirts
  17. Crainates
    • The origin of a head opened up a completely new way of feeding for chordates: active predation
    • share some characteristics: a skull (at least a partial skull), brain, eyes, and other sensory organs
  18. Derived characters of crainates
    • One feature unique to craniates is the neural crest, a collection of cells near the dorsal margins of the closing neural tube in an embryo
    • Neural crest cells give rise to a variety of structures, including some of the bones and cartilage of the skull
    • Craniates have a heart with at least two chambers, red blood cells with hemoglobin, and kidneys
  19. Myxini
    • The least derived surviving craniate lineage is Myxini, the hagfishes
    • Hagfishes have a cartilaginous skull and axial rod of cartilage derived from the notochord, but lack jaws and vertebrae
  20. Vertebrates are?
    Vertebrates are craniates with a backbone
  21. Characters of vertebrates
    • Vertebrae enclosing a spinal cord
    • An elaborate skull
    • Fin rays, in the aquatic forms
  22. Petromyzontida
    • Lampreys represent the oldest living lineage of vertebrates
    • They are jawless vertebrates inhabiting various marine and freshwater habitats
  23. Gnathostomes
    • vertebrates with jaws
    • Today, jawed vertebrates, or gnathostomes, outnumber jawless vertebrates
    • An enlarged forebrain associated with enhanced smell and vision
    • In aquatic gnathostomes, the lateral line system, which is sensitive to vibrations
  24. lateral line system is what?
    a pressure sensor
  25. Chondrichthyes
    • have a skeleton composed primarily of cartilage
    • The cartilaginous skeleton evolved secondarily from an ancestral mineralized skeleton
    • The largest and most diverse group of chondrichthyans includes the sharks, rays, and skates
  26. 3 ways embryo (shark) can develop: Chondrichthyes
    • Shark eggs are fertilized internally but embryos can develop in different ways:
    • –Oviparous: eggs hatch outside the mother’s body
    • –Ovoviviparous: the embryo develops within the uterus and is nourished by the egg yolk
    • –Viviparous: the embryo develops within the uterus and is nourished through a yolk sac placenta from the mother’s blood
  27. osteichthyes
    • includes the bony fish and tetrapods
    • Nearly all living osteichthyans have a bony endoskeleton
    • Aquatic osteichthyans are the vertebrates we informally call fishes
    • Most fishes breathe by drawing water over gills protected by an operculum
    • Fishes control their buoyancy with an air sac known as a swim bladder