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Biology 03050, Invertebrate Zoology

Handout for Week 5: CNIDARIANS

Lab manual: Hickman et al., 9th ed., Exercise 9, pp. 127-142


WORD BANK (terms that you are responsible for):

1. aboral view

2. basal disc

3. body wall

4. bud (asexual)

5. cnidocil

6. cnidocyte

7. comb jelly,

Phylum Ctenophora

8. comb plates (rows), on

comb jelly

9. coral, Class Anthozoa

10. ectoparasite

11. egg

12. epidermis

13. feeding polyp

14. female

15. float (bladder)

16. gastrodermis

17. gastrovascular cavity

18. gonad

19. hydra, Class Hydrozoa

20. hypostome

21. jellyfish, Class Scyphozoa

22. male

23. medusa

24. mesoglea

25. mouth

26. nematocyst

27. Obelia, Class Hydrozoa

28. oral arm

29. oral view

30. ovary

31. pharynx

32. polyp

33. Portuguese man-of-war,

Class Hydrozoa

34. radial canal

35. reproductive polyp

36. rhopalium, -a

37. septum, -a

38. subgenital pit

39. tentacle

40. testis



Using your lab manual for guidance, perform those parts of Exercise 9 listed below:

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.


your own notes and drawings (on the back or in your notebook):


|main page| |background| |03028: Physiology| |03048: Anatomy|

|03050: Invertebrate Zoology| |03051: Vertebrate Zoology| |03074: Economic Botany|


Please send comments and questions to: cronewil@hvcc.edu


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