1. PHYLUM: CNIDARIA

2. Classes of Cnidaria Class Hydrozoa (e.g., Hydra, Obelia)
Class Scyphozoa (e.g., Aurelia)
Class Cubozoa (e.g., cube jellies)
Class Anthozoa (anemones and corals)
Subclass Hexacorallia (sea anemones, hard corals)
Subclass Octocarallia (sof corals)

3. General Characteristics
Entirely aquatic; mostly marine, but with a few freshwater species;
may be solitary or colonial
Metazoan, with true tissues.
Diploblastic – two germ layers
outer cell layer known as ectoderm (epidermis),
inner cell layer known as endoderm (=gastrodermis),
with a non-cellular mesoglea between.

4. General Characteristics
The internal body space (gastrovascular cavity) lined with gastrodermis
has a mouth, but no anus (incomplete digestive tract)
Possess cnidocytes with special cell organelles - nematocysts, used for defense and offense

5. General Characteristics cont.
Phylum exhibits polymorphism
Metagenesis- alternation of generation
Polyp (often sessile) and the medusa (free swimming).
The polyp stage reproduce asexually, while the medusa stage usually reproduces sexually
Reproduction is asexual by budding and/or sexual, producing a ciliated planula larva

6. Figure 13.02
Two general
body forms

8. Class Hydrozoa solitary or colonial
alternation of asexual polyps and sexual medusae

9. Figure 13.09

11. Life Cycle of Hydra
SEXUAL
REPRODUCTION
ASEXUAL
REPRODUCTION

12. Hydra with Bud
Ovary
Bud

13. Hydra with Gonads
Testes

14. Gastrovascular
cavity
Hydra c.s.
Epidermis
Mesoglea
Gastrodermis

15. Figure 13.09
Obelia Life Cycle

16. Obelia - Medusa
Gonad
Tentacle
Gastrovascular cavity

17. Obelia – Hydroid colony
Gastrozoids = Hydranth
Gonozoids = Gonangium

18. Obelia – Hydroid Colony
Gonozooid
Hydrozooid

19. Gonionemus
Gonad

20. Physalia – Portuguese Man-O-War - a colony, not an individual
It is not a jellyfish!!

21. Class Scyphozoa True Jellyfishes
polyp stage reduced or absent
bell-shaped medusae
margin of bell with eight notches which are provided with sense organs
all marine

23. Aurelia - Medusa

24. Aurelia - Planula larva

25. Aurelia - Scyphistoma

26. Aurelia - Strobila

27. Aurelia - Ephyra

28. Class – Anthozoa Sea Anemones and Corals
all species occur as polyps only, no medusae;
gastrovascular cavity partitioned by at least eight septa with nematocysts
Solitary or colonial
all marine.

31. Some Hydrozoans

32. Figure 13.07

33. 0022.jpg
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35. Figure 13.15a

36. Figure 13.15b

37. Some Scyphozoans

38. Jellyfishes

39. Figure 13.16

40. Figure 13.17

41. Some Anthozoans

42. Sea Anemones

43. Figure 13.25

45. Figure 13.29

47. Corals

48. Figure 13.32

49. Figure 13.33a

50. Figure 13.33b

51. Figure 13.28

52. 0039.jpg
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53. 0041.jpg
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54. 0047.jpg
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55. 0048.jpg
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56. Figure 13.26b

57. Figure 13.26c

58. 0049.jpg
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60. Phylum Ctenophora
The Combjellies

61. General Characteristics
Biradial symmetry
Eight rows of comb plates
Tentacles possess colloblasts
Triploblastic (three cell or germ layers)
Mesoglea (loose mesenchyme) is jelly-like material strews with fibers and amebocytes and contains true muscle cells
Aboral sense organ (statocyst)
Digestive system: mouth, pharynx, stomach, branched canals and anal pore
Monoecious, with both eggs and sperm produced from endodermal lining of digestive canals beneath comb plates

62. Figure 13.36

63. Figure 13.36a

64. Figure 13.38

65. Figure 13.38a

66. Figure 13.38b

67. Figure 13.35

68. 0002.jpg
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