Chordate Phylogeny

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Chordate Phylogeny
2015-09-30 17:37:02
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  1. Taxonomy of the kingdom Animalia
    - Phylum __
    - Phylum __
    --> Subphylum __
    --> Subphylum __
    --> Subphylum __
    ------> __
    ------> __
    • Hemichordata
    • Chordata

    • Urochordata
    • Cephalochordata
    • Craniata

    • Hagfish (no vertebrae)
    • Vertebrata (vertebrae)
  2. Where are we?
  3. Hagfish lack __ but have the characteristics and vertebra do have them, as well as diagnostic characteristics
  4. Chordate Diagnostic Characteristics


    Dorsal, hollow nervous system

    Postanal tail
  5. notochord
    rod shaped structure consistent of living cells; it is an axial support; for some organisms, it is the only support; in higher organisms, it is replaced by the vertebral column

    usually present at least in the embryo and sometimes only in the embryo
  6. Pharynx
    “throat”; a tube that is part of digestive system; not just a pharynx, but a pharynx that shows pouches or slits to the outside or at least in the wall; slits can go outside of the organism or the walls
  7. 1) __  found in the pharynx during development are __ in aquatic animals that use __

    2) Associated with it is an __, which is a __; __ in the nonchordates

    1)Many anatomists believe the __ is a forerunner to our __
    • Gill slits
    • permanent ones
    • gills for respiration

    • endostyle
    • glandular groove on the bottom (floor) of the pharynx
    • secretes mucus

    • endostyle
    • thyroid gland
  8. Dorsal, hollow NS:
    dorsal meaning toward the back; hollow meaning there is a cord running through it

    consists of brain and spinal cord and contains a central cavity (neurocoel)
  9. Postanal tail: __
    tail behind the anus; can be retained or not
  10. Fate of the notochord:

    in protochordates
    In the protochordates (eurichordata and cephalochordate), the notochord remains as the chief axial support
  11. Fate of the notochord:

    in agnathan
    In agnathan (jawless fish and most primitive), there are lateral neural cartilages that are located on the sides of the notochord; the notochord remains, but support is helped by the lateral cartilages
  12. Fate of the notochord:

    in fish and amphibians
    Fish and amphibian: the notochord persists the length of the trunk and tail –but even though it persists, it’s really constricted within the centrum of the vertebraeIn head region, it is incorporated into the head of the skull
  13. Fate of the notochord:

    reptiles, birds, mammals
    Reptiles, birds, and mammals: notochord almost disappears during development of the animal
  14. Fate of the notochord:

    in other organisms
    In some organisms, you may see remains of the notochord in the body. In mammals, there’s an area in the body known as the pulpy nucleus, a structure in the body of eeach vertebrate and contains the remains of the notochord
    Acorn Worms are most well known hemichordates
  16. What do hemichordates have?
    • –They do have: Dorsal, hollow nerve cord
    • Gill slits/ pharynx
    • Postanal tail
    • Short diverticulum (outpocketing) off of the gut, which is called the stomochord (this is where they differ)
    • –The stomochord is not homologous to the notochord; has a different origin
  17. In the subphylum urochordata, explain the larva and adult in terms of diagnostic characteristics?
    Only the larvae show the diagnostic characteristics(adult shows little of the diagnostic characteristics (left))

    notochord, dorsal nerve cord, pharyngeal clefts
  18. Metamorphosis of an ascidian
    Going from a free-swimming larva through metamorphosis into a sessile adult

    - Has DC in larval stage, but not in adult

    Adults are sessile and lose some of the chordate characteristics
    Cephalo: means head region; also aquatic animals

    • They have: 
    • - notochord
    • - dorsal hollow NS
    • - pharyngeal gill slits
    • - circulatory system (vertebrate pattern with pumping vessels but no heart)
  20. Subphylum: Vertebrata

    What are the superclasses?
    SUPERCLASS-PICES and TETRAPODA (meaning on land)
  21. Superclass pices
    • Class Agnatha: jawless fish
    • Class Placodermii
    • Class Chondricthyes: dogfish shark/ cartilaginous
    • Class Acanthodii
    • Class Osteichthyes: bony fish that you eat
  22. Superclass tetrapoda
    • Class Amphibia
    • Class Reptilia
    • Class Aves
    • Class Mammalia
    • Not exclusive to chordates
    • There are characteristics that are shared by many chordata, but are not diagnostic.
    • They are often seen in vertebrates
  24. What are the cranial characteristics?
    • They are:Regional differentiation (head, neck, chest, etc)
    • Bilateral symmetry
    • Metamerism (the serial repetition of a structure)
    • Vertebral column (Except for hagfish)
    • Coelom (a endodermally lined cavity; serous membrane lining the cavity and covering the viscera, which are internal organs)
    • There are peritoneal, pericardial, and pleural cavity in higher vertebrates.
    • Ventrally located heart with blood flow caudal (going toward the back) by means of the dorsal artery
  25. In order to be considered a coelom, what?
    it needs a serous membrane Ventrally located heart with blood flow caudal (going toward the back) by means of the dorsal artery
  26. The Craniata, or craniates, include all animals having a __.
    skull (or cranium, hence their name), be it cartilaginous or bony
  27. A skull is a __.
    box of hard tissues which encloses the brain, olfactory organs, eyes, and internal ear
  28. Craniates comprise __
    all fishes - including such jawless fishes as hagfishes and lampreys - amphibians, reptiles, birds and mammals, including Man.

    1) Semicircular canals
    • Agnatha have one or two
    • Gnathostomes have three

    Jointed, paired lateral appendages
    • Agnatha have none
    • Gnathostomes do (number depends on animal)

    • Agnatha have none
    • Gnathostomes have jaws
  32. semicircular canals are __
    located in the ear for balance