Subphylum Urochordata Flashcards
urochordates are marine non-vertebrate chordates consisting of three classes, what are they?
- Ascidiacea, tunicates, or sea squirts
- Larvacea
- Thaliacea
Among the nonvertebrate chordates the pharynx functions as?
A filterfeeding appartus
what is the endostyle of urochordates capable of?
producing mucus, removing environmental iodine, and synthesizing compounds containing the iodine.
in the adult. tunicate, what two definitive chordate characteristics are absent?
notochord and dorsal hollow nerve cord
in adult tunicates, the nerve cord is modified into?
a solid ganglion lying in the mantle between the two siphons
T/F: In contrast to the adult tunicates, the larval had a well-developed notochord.
TRUE
how does the nerve cord show in the larval form of a tunicate?
appears as a clear tube-like structure dorsal to the notochord and extends from the tail tip well into the body
what is the statocyst function in the larval tunicates?
organ of balance
what is the ocellus function in the larval tunicates?
functions as a photoreceptor
how long does the larval stage last in tunicates?
24-48 hours
what do larval tunicates do in the first 24-48 hours of life?
swim away from the parents and surfaces because of positive phototaxis and negative geotaxis
what happens after the 24-48 hours pass in larval tunicates?
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.