Subphylum Urochordata

Question 1

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

Answer 1

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

Question 2

Among the nonvertebrate chordates the pharynx functions as?

Answer 2

A filterfeeding appartus

Question 3

what is the endostyle of urochordates capable of?

Answer 3

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

Question 4

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

Answer 4

notochord and dorsal hollow nerve cord

Question 5

in adult tunicates, the nerve cord is modified into?

Answer 5

a solid ganglion lying in the mantle between the two siphons

Question 6

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

Answer 6

TRUE

Question 7

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

Answer 7

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

Question 8

what is the statocyst function in the larval tunicates?

Answer 8

organ of balance

Question 9

what is the ocellus function in the larval tunicates?

Answer 9

functions as a photoreceptor

Question 10

how long does the larval stage last in tunicates?

Answer 10

24-48 hours

Question 11

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

Answer 11

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

Question 12

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

Answer 12

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.