MARINE BIOLOGY: LECTURE 3



Study Questions, Lecture 3: Platyhelminthes, Nematoda, Annelida

January 11, 2008

Disclaimer: You are responsible for all material presented in class. These questions are meant to aid in your studies, but you should study the material itself, not just answers to the study questions! I suggest you learn the material and then use these study questions to quiz yourself.

1. In which type of habitat do you find Platyhelminthes?

2. What are the key derived characters that arise between the Cnidaria and Platyhelminthes branchpoints? List and describe them.

3. Compare the tissue layers present among the Porifera, Cnidaria and Platyhelminthes.

4. Why is the presence of mesoderm significant?

5. What advantages might there be to having radial symmetry? What advantages might there be to having bilateral symmetry?

6. List and describe the four key differences between protostomes and deuterostomes. Also know which of the major phyla (i.e. those we are covering in this course) are protostomes and which are deuterostomes.

7. What structure does Planaria use for feeding? Briefly explain how it works.

8. What are the key functions of the gastrovascular cavity in the Platyhelminthes? How does this compare to those in Phylum Cnidaria? How do Cnidarians and Platyhelminthes eliminate waste from their digestive system without a separate anus?

9. What is the function of the “flame bulb system?” How is water drawn into the flame bulb system? (NOTE: The flame bulb system is specific to Platyhelminthes, while “protonephridia” is a more general term.)

10. Describe the nervous system of Platyhelminthes. Specifically, is there a brain? Are there nerve cords and if so, where are they located?

11. How does a flatworm move? Describe the two distinct mechanisms.

12. Are there male and female flatworms? How does fertilization occur for the marine flatworms seen in the video (specific term and description?)

13. What is one unusual function of the Platyhelminthes penis (in addition to its role in mating?)

14. What is the cuticle of Nematodes, and what is it comparable to in the Phylum Arthropoda? Where is the cuticle located with respect to the epidermis? Is the cuticle considered a true tissue?

15. What is the key derived character that arises between the Platyhelminthes and Nematoda branchpoints? List and describe it.

16. What is a body cavity, in general terms? Describe several functions of a body cavity, including why it might be advantageous to have some type of body cavity.

17. What is a pseudocoelom? How does it differ structurally from a true coelom (a.k.a. “eucoelom”?)

18. What do I mean by "Nematodes suck"? What specific part of their body creates the suction?

19. In which key ways does the digestive system of Phylum Nematoda differ from the gastrovascular cavities of the Cnidaria and Platyhelminthes?

20. Where does gas exchange occur in the Nematoda?

21. Why can nematodes move only in a side-to-side motion, but not directly forward or backward? What is the role of the cuticle in movement?

22. Describe the nervous system of Phylum Nematoda members. Specifically, do they have a brain? Do they have nerve cords and if so, where are they located? Do they have ganglia and if so, where are they located? What are ganglia?

23. Why is the nerve-muscle connection of nematodes considered unique?

24. What is the key derived character that arises between the Nematoda and “Annelida/Mollusca/Arthropoda” branchpoint? List and describe it.

25. What does a true coelom (or “eucoelom”) as in Phylum Annelida have that the pseudocoelom (for Phylum Nematoda) does not? As a result, what can annelids do that nematodes cannot?

26. Describe some advantages to having body segmentation.

27. Name the three classes of Phylum Annelida, and describe the major differences among the three in terms of setae, cephalization, segmentation and presence/absence of parapodia.

28. What type of digestive system do the Annelids have, and what is an obvious advantage of this type of digestive system for the Annelida (not really seen in the Nematoda even though they also have this type of digestive system?) Provide examples to illustrate your answer.

29. The annelids are the first phylum in which we see any type of circulatory system. Do they have an open or closed circulatory system? (Be sure you know what these terms mean.) What causes blood to be pumped throughout their body? (NOTE: Answer based on the Oligochaeta.)

30. What are the key locations of gas exchange for the Class Oligochaeta? What additional gas exchange surface exists for members of Class Polychaeta?

31. Describe the nervous system of Phylum Annelida members. Specifically, do they have a brain? Do they have nerve cords and if so, where are they located? Do they have ganglia and if so, where are they located? What are ganglia?

32. What feature enables an annelid to move forward by peristalsis, whereas a nematode cannot, but is able to move only side to side, but not forward or backward (unless it has something to push against)?

33. Describe how members of each of the three Classes of Phylum Annelida feed. Be sure you know the three types of substances that are secreted to aid in the blood sucking behavior of leeches (Class Hirudinea.)

More on next page—questions that link content together!

Questions to begin answering and building upon as we cover Kingdom Animalia… Note that the phyla up through Annelida have been presented in order of increasing complexity of body systems.

34. Describe the key developments that are hypothesized to have occurred at each of the major branch points as the Kingdom Animalia evolved, according to the traditional model of phylogeny (i.e. body plan characteristics). In addition, explain the adaptive significance of each of the “new” or “derived” features for the animals (i.e. how does it aid in the animal’s existence?). You should also know where each of the phyla we studied should be placed on this evolutionary continuum.

35. (Related to above question…) For each phylum studied, you should be able to compare:

• symmetry

• number/type of tissue layers (or whether it has them at all)

• body cavity: whether it exists, and type

• considered Protostome, Deuterostomes or neither

36. Compare the digestive systems among phyla, including whether they have one, what it is called (if something special), its basic appearance, whether it is complete. (And of course, know what is meant by “complete digestive system”.) How might having a complete digestive system be an advantage over an incomplete one, or none at all?

37. Be able to describe how a particular organism obtains food and eats, to the level described in lecture and/or lab.

38. What are the functions of an excretory system? Which groups studied have excretory systems? Know specific names for these structures and/or how they work if discussed in lecture and/or lab.

39. Know where gas exchange occurs for members of different phyla, and where applicable, for members of different classes.

40. Know whether a particular group has a circulatory system and if so, whether it is open or closed. (Know what is meant by an open vs. closed circulatory system.)

41. Compare the nervous systems among phyla.

• Which one has no nervous system?

• Which have brains?

• Which have nerve cords (i.e. direct pathways for nerve conduction?) Where are these nerve cords located?

• Which have ganglia? Where are the ganglia located? What are ganglia?

• Which can conduct action potentials bidirectionally?

42. Describe aspects of reproduction to the level described in lecture and/or lab (variable coverage.)

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download