8.4: Data Analysis and Discussion

Instructions

Discussion should be typed (double spaced, size 12 font and standard 1” margins). There are no specific length requirements for this discussion but be sure to address all the components in the prompt below. You will submit this discussion along with your sketches and observations for your completed lab report.

Prompt/Questions to Address

Write a discussion for this experiment which explores the characteristics and evolutionary significance of the animals observed during this lab. Be sure to address each of the following in your discussion:

1. Examine the body plan of sponges. Discuss how the sponge body plan represents an evolutionary transition between unicellular protists and more complex multicellular animals.
2. Examine the body plan of cnidarians. Compare the organization of tissues in cnidarians with those in sponges. What new level of complexity is introduced in cnidarians?
3. Examine the body plan of flatworms. What evidence of cephalization did you observe in the planarian? How might this contribute to its behavior and interaction with the environment?
4. Evaluate the evolutionary relationships between these different animals. Across these three groups, what trends do you see in the development of tissues, organs, and organ systems? (HINT: Based on your observations, describe the overall trend in body organization and complexity from Porifera → Cnidaria → Platyhelminthes.).