Phylum Cnidaria – Corals, Jellies, and Anemones
There are 3 sections of this investigation; pre-lab questions, hands-on investigation and
post-lab questions. You will need to refer to your text to answers the questions and
identify the different parts of the specimens. Please answer all questions in complete
sentences.
Pre-lab questions – You will have 30 minutes to answer the questions below. You will NOT begin the
hands-on section of this investigation until you do so.
1.
2.
3.
4.
5.
What is diploblastic tissue-level organization?
What is radial symmetry?
Why is it advantageous for a sedentary animal to have radial symmetry?
How does the term “alternation of generation” apply to members of the phylum Cnidaria?
Identify and describe the five classes of Cnidaria. Be sure to include characteristics that differentiate
one class from another.
6. What cell type is unique to the cnidaria?
Post- lab questions – Answer the questions below for homework whether or not you have finished the
hands-on portion of this investigation.
Refer to figure 1 for questions 1-4.
1.
2.
3.
4.
According to the cladogram below, what are the ancestral characters of the phylum Cnidaria?
What derived character(s) distinguishes the scyphozoan/anthozoan clade from the hydrozoans?
What derived character distinguishes the anthozoans from all other Cnidarians.
According to this cladogram members of what class are probably most closely related to ancestral
cnidarians?
Figure 1. Cnidarian Phylogeny
Refer to figure 2 to answer questions 5 and 6
Figure 2. Life cycle of Aurelia
5. Label each stage of the cycle.
□ Ephyra
□ Medusa
□ Planula
□ Scyphistoma
□ Strobila
6. Indicate the part of the life
cycle in which the organism
undergoes asexual and
sexual reproduction.
Figure 3. Box jelly
Refer to figure 3 to answer questions 7 and 8
7. To what class does this organism belong? Justify
your response.
8. Using your knowledge of Cnidarian morphology,
try and label the following parts:
□ rhopalia
□ manubrium
□ tentacles