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PHYLUM: CNIDARIA

PHYLUM: CNIDARIA. 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).

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PHYLUM: CNIDARIA

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  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

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

  8. Figure 13.09

  9. Life Cycle of Hydra SEXUAL REPRODUCTION ASEXUAL REPRODUCTION

  10. Hydra with Bud Ovary Bud

  11. Hydra with Gonads Testes

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

  13. Figure 13.09 Obelia Life Cycle

  14. Obelia - Medusa Gonad Tentacle Gastrovascular cavity

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

  16. Obelia – Hydroid Colony Gonozooid Hydrozooid

  17. Gonionemus Gonad

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

  19. 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

  20. Aurelia - Medusa

  21. Aurelia - Planula larva

  22. Aurelia - Scyphistoma

  23. Aurelia - Strobila

  24. Aurelia - Ephyra

  25. 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.

  26. Some Hydrozoans

  27. Figure 13.07

  28. 0022.jpg

  29. Figure 13.15a

  30. Figure 13.15b

  31. Some Scyphozoans

  32. Jellyfishes

  33. Figure 13.16

  34. Figure 13.17

  35. Some Anthozoans

  36. Sea Anemones

  37. Figure 13.25

  38. Figure 13.29

  39. Corals

  40. Figure 13.32

  41. Figure 13.33a

  42. Figure 13.33b

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