A tunicate looks like a sponge. How could a biologist distinguish it from a member of the Porifera?

Question

A.  Tunicates do not filter feed.
B.  Only tunicates produce gametes.
C.  Unlike tunicates, sponges are symmetrical.
D.  Tunicates have a stomach.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

Gather Content
· What do you already know about tunicates?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

D.  Tunicates have a stomach.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses tunicates.
· What type of thinking is required?
        o This question is asking you to take what you already know and apply it to this unfamiliar situation.

Gather Content
· What do you already know about tunicates?
        o Tunicates are members of the subphylum Urochordata. Their morphology is simple on the outside, but more complex on the inside.
        o Water enters through the incurrent siphon and exits through the excurrent siphon. The pharynx is lined with cilia that draw a stream of water into the pharynx, where microscopic food particles become trapped in a mucous sheet secreted from a structure called an endostyle. Captured food particles pass into the stomach and through the intestine.
        o Tunicates change so much as they mature and adjust developmentally to an immobile, filter-feeding existence that it is difficult to discern their evolutionary relationships solely by examining an adult. Many adult tunicates secrete a tunic, a tough sac composed mainly of cellulose, a substance frequently found in the cell walls of plants and algae but rarely found in animals. The tunic surrounds the animal and gives the subphylum its name. Colonial tunicates may have a common sac and a common opening to the outside.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Sponges are morphologically simple on the outside and the inside, but tunicates have a gut and stomach inside. The stomach, therefore, identifies the sponge-like animal as a member of the Urochordata.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that tunicates have a full digestive tract inside?