Amphioxus

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  1. External anatomy of the amphioxus (the lancelet)
    • Slender body and is aquatic
    • Somewhat compressed laterally
    • Degenerate head with oral hood surrounding it that has buccal cirri
  2. Image Upload
    Dorsal fin

    metapleuro

    atripore

    Atriofin that goes from atriopore to anus

    Caudal fin
  3. External anatomy again

    -- midgut?
    External anatomy

    There is an outpocketing under the mid gut (in yellow) called the hepatic diverticulum or mid gut cecum; forerunner of the liver but does not function at all like a liver

    From the mid gut, there is a constriction of the neural tube; and, the narrow region is the ???
  4. buccal cirri
    tentacle like projections on the head end
  5. Explain the mouth region.
    • Once the food enters the mouth, it goes to the pharynx, which has a bunch of slits in it as demonstrated above
    • Those slits are protected by gill bars, protecting the slits
    • There are also horizontal structures that go across one slit to the next and they keep the gills from closing; these are synapticula, which help prevent the collapse of the slits
  6. Digestive system
    • Filter feeder
    • Hood with buccal cirri play role in digestive system because it helps bring food back into oral hood
  7. What is a filter feeder?
    (animals filter water and microorganisms that are coming in; they need a mechanism to draw that water into their oral hood; the mouth is at the back of the vestibule, not at the entrance of the oral hood)
  8. Vestibule is __
    opening under oral hood
  9. On inside of oral hood are __

    The whole structure is __ located in the __ and __ of __; made of __; help __; called the __
    • patches of cirrated epitelium
    • horse-shoe shaped
    • side and roof of oral hood
    • ciliated epithelium
    • project water and food toward the mouth
    • wheel organ
  10. - To assist in movement, the highlighted area has a place called __, which does what?
    ___ extend out of the oral hood; they are __ that help create currents to bring the food back into the structure, which is the __.
    • Hatscher’s pit
    • secretes mucus
    • fingerlike projections
    • ciliated epithelial patches
    • wheel organ
  11. At the back of the vestibule is a structure called the __, which has __ as a a part of that membrane. Those tentacles, when closed, will not __because __; and, when the tentacles are open, then the mouth is available; tentacles __
    vellum

    thin tentacles

    • allow passage outside of vestibule
    • the slit in the vellum is the mouth

    guard the mouth
  12. Two grooves in the pharynx: one in the roof and one in the floor

    Explain the floor one.
    In the floor of the pharynx is the endostyle (in green), a structure that secretes mucus
  13. Two grooves in the pharynx: one in the roof and one in the floor

    Explain the roof one.
    • In the roof of the pharynx is the epipharyngeal groove (blue)
    • The whole groove is ciliated so that the food can get caught and be pushed through the pharynx into the midgut
  14. After midgut, the __ is next, where solid wastes come out

    In terms of the __, the __(4) , as well as __,are in the atrium, the last of which are in the floor
    The gametes exit through the __as well
    • hind gut
    • atrium
    • pharynx, stomach, diverticulum, and some of the hind gut
    • gonads
    • atriopore
  15. Circulatory System
    - skin
    - function of skin
    - function of circ system
    - system type
    - components
    - speed
    • Unlike most, this circulatory system does not function in respiration
    • Amphioxis uses skin as respiratory organ
    • The function is to transport the digestive materials
    • It has an open system; it has arteries and veins but no capillaries; pretty sluggish (open systems are very sluggish)
    • It does not have a heart and it lacks RBCs; no capillaries
    • Very slow
Author:
DesLee26
ID:
307667
Card Set:
Amphioxus
Updated:
2015-09-11 16:38:55
Tags:
Vertebrates
Folders:
Seitchik
Description:
Test One
Show Answers: