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 ScyphozoaTrue 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 – AnthozoaSea 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

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