Primitive Chordates Origin of vertebrates

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Primitive Chordates Origin of vertebrates
2015-02-05 14:48:24
Vertebrate Anatomy

Vertebrate anatomy
Show Answers:

  1. Immutable
    Unchanging over time; unable to be changed
  2. Homology
    When different species have the same structures or genes because of a shared ancestor
  3. Define clade.
    All organisms within a single evolutionary lineage; stemming from a common ancestor (can also be called taxon)
  4. Define ancestral (primitive)
    Appearing earlier in the fossil record, ancestral character state
  5. Define derived.
    Appearing later in the fossil record as a new evolutionary innovation, descendent character state
  6. Define analogous structures.
    Organs or structures having similar functions but not sharing an ancestor
  7. Describe a heterocercal caudal fin.
    • A tail fin with unequal lobes in which the vertebral column turns upward into the larger lobe as in sharks
    • Provides lift while swimming, counteracting the tendency to sink
    • They need these fins because they lack a swim bladder
  8. Describe a homocercal caudal fin.
    • Symmetrical tail fin extending beyond the end of the vertebral column as in most bony fishes
    • These fish have swim bladders for buoyancy so they do not need the heterocercal tails
  9. Biological species concept
    A group of similar-looking individuals capable of successfully interbreeding
  10. Phylogenetic species concept
    A genetically distinct group reproductively isolated from other such groups (i.e., gene flow restricted)
  11. Classification System (general to specific)
    • Domain
    • Kingdom
    • Phylum
    • Class
    • Order
    • Family 
    • Genus
    • Species
    • Did King Philip Come Over For Good Spaghetti
  12. Describe the taxonomic unit system.
    • Each successful higher unit contains fewer and fewer shared traits 
    • The higher the taxonomic unit the less closely related the animals in that group are
    • Class has fewer shared characteristics than family
  13. Describe Deuterostomes
    • The blastopore (an opening occurring in early embryo) becomes the anus. (Anus first mouth second)
    • Includes echinoderms, hemichordates, and chordates
  14. Describe protostomes.
    • Blastoprore (an opening occurring in early embryo) becomes mouth. (Mouth first, anus second)
    • Includes Molluscs, Annelids and arthropods
  15. Blastopore
    An opening occurring early in embryo
  16. Phylum Chordata
    Vertebrates and Invertebrate chordates
  17. Four chordate morphological characteristics
    • Notochord - stiff supporting rod along dorsal part of body, under dorsal nerve cord
    • Pharyngeal gill slits - more efficient food intake
    • Dorsal hollow nerve cord
    • Post-anal tail
  18. Why is thyroxine so important to chordates?
    • Adequate growth 
    • Development
    • Tissue Differentiation
    • Metabolic rate
  19. What do all chordates have that produce thyroid hormones.
    • They all have cells that produce these. Endostyle or thyroid gland
    • Endostyle = glandular groove in floor of pharynx; involved in filter feeding
  20. What is an endostyle?
    A glandular groove in floor of pharynx; involved in filter feeding
  21. In vertebrates, what is a major importance of thyroxine?
    Proper brain development and for reproduction
  22. Georges Cuvier
    • Saw species as immutable 
    • Used evidence from fossils
  23. Richard Owen
    • Saw species as immutable
    • How to explain corresponding body parts e.g., homologous structures
  24. Darwin and Wallace
    • Species are not fixed
    • Present characters must be derived from already existing structures
  25. Pterobranchs
    • Tiny, rare marine animals that form plant-like colonies; individuals project like small "flowers" at the end of a secreted tube
    • Possess one pharyngeal gill slit, but no other chordate characteristics
    • Filter feed by ciliary action
  26. Related Phylum - Hemichordata
    • Pterobranchs (class pterobranchia)
    • Acorn worms (class enteropneusta)
  27. Acorn Worms
    • Elongated worm-like animals that burrow in tidal mud flats
    • Anterior end with a probosics (used in burrowing) followed by a collar (contains mouth) - these structures also found in pterobranchs
    • Well developed pharyngeal slits
    • Dorsal nerve cord (not complete)
    • Stomocord - stout pouch of support tissue
  28. Hox Genes
    • Genes involved in early development
    • Produce reversed dorsal and ventral body pattern between chordates and all other animals, including hemichordates
  29. Phylum chordata consists of 3 subphyla
    • Urochordata (tunicates or sea squirts)
    • Cephalochordata (lancelets - amphioxus)
    • Vertebrata (vertebrates or craniata - hagfish +                            vertebrates)
  30. Urochordates (tunicates)
    • Marine animals that may be solitary or colonial
    • Adults have sac-like shape with outer covering a "leathery" tunic (cellulose)
    • Filter feeders using pharyngeal gill slits
    • Larvae are free swimming and have all 4 chordate characteristics
    • Larvae metamorphose into sessile adults - notochord, dorsal nerve cord and post-anal tail degenerate
  31. Cephalochordates (amphioxus)
    • Elongated, vaguely fish-like marine animals that live mainly buried in sand or silt with the head region protruding
    • Are capable of swimming
    • Possess all 4 chordate characteristics as adults
    • Filter feeders using pharyngeal gill slits
    • No paired fins present only metapleural folds
    • Possess segmentally arranged muscle masses (myomeres)
  32. Vertebrata (vertebrates)
    • Characterized by cephalization
    • This necessary because vertebrates are active animals and need to perceive info from front of body
    • Possess vertebral column (backbone)
    • Specialized kidney tubules
    • Fish, amphibians, reptiles, birds, mammals