Subphylum Urochordata Flashcards

1
Q

urochordates are marine non-vertebrate chordates consisting of three classes, what are they?

A
  1. Ascidiacea, tunicates, or sea squirts
  2. Larvacea
  3. Thaliacea
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2
Q

Among the nonvertebrate chordates the pharynx functions as?

A

A filterfeeding appartus

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3
Q

what is the endostyle of urochordates capable of?

A

producing mucus, removing environmental iodine, and synthesizing compounds containing the iodine.

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4
Q

in the adult. tunicate, what two definitive chordate characteristics are absent?

A

notochord and dorsal hollow nerve cord

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5
Q

in adult tunicates, the nerve cord is modified into?

A

a solid ganglion lying in the mantle between the two siphons

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6
Q

T/F: In contrast to the adult tunicates, the larval had a well-developed notochord.

A

TRUE

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7
Q

how does the nerve cord show in the larval form of a tunicate?

A

appears as a clear tube-like structure dorsal to the notochord and extends from the tail tip well into the body

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8
Q

what is the statocyst function in the larval tunicates?

A

organ of balance

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9
Q

what is the ocellus function in the larval tunicates?

A

functions as a photoreceptor

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10
Q

how long does the larval stage last in tunicates?

A

24-48 hours

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11
Q

what do larval tunicates do in the first 24-48 hours of life?

A

swim away from the parents and surfaces because of positive phototaxis and negative geotaxis

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12
Q

what happens after the 24-48 hours pass in larval tunicates?

A

the taxes reverse. the larva then seeks a dark area at the bottom and attaches to a substratum using adhesive organs. then reabsorbs it tail and metamorphoses into the sessile adult.

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13
Q
A
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