1) Read the introduction to the phylum on pp. 127-128.

2) Exercise 9A: Class Hydrozoa will include a look at three hydrozoans: solitary hydras, colonial Obelia with two polyp types, and the colonial Portuguese man-of-war with four polyp types.

hydra: examine a live hydra and study its behavior and external structures, concentrating on the terms listed above. Examine a prepared cross section slide of hydra to gain an appreciation of the layers of the body wall. Finally, examine slides of asexually and sexually reproducing hydras. Be able to distinguish among budding, male, and female individuals.

Obelia: examine both polyp and medusa stage slides. What are the two polyp types in the colony?

man-of-war: note the float (possibly a modified polyp) and the number and types of individuals dangling from it. Why is a man-of-war not a jellyfish?

3) Exercise 9B: Class Scyphozoa. Aurelia, the moon jelly. Using appropriate dissection equipment and technique, examine a preserved jelly as method described in the manual.

4) Exercise 9C: Class Anthozoa. We have preserved samples of various hard corals: what do the small holes in those pieces represent? What does a coral reef represent? We also have samples of sea anemones. Note external and internal features that are distinctive about these large solitary polyps.

5) Phylum Ctenophora: comb jellies (if available). Although not mentioned in the lab manual, comb jellies, particularly the common sea walnut Pleurobranchia, are other common radiate animals. Make observations of the external structures of a specimen, using your text (Ch. 18, pp. 411-412) to firm up your understanding of the differences between ctenophores and cnidarians.