Taxonomy and Life Cycles of Phylum Coelenterata

1. Phylum Coelenterata(Cnidaria & Ctenophora)

2. Phylum Cnidaria • Diploblastic organisms • Radially symmetrical • Dimorphic • Cnidocytes • ~10,000 species • Aquatic

3. Taxonomic Characteristics • Diploblastic • Gastroderm & Musculo-epithelial tissues

4. Taxonomic Characteristics • Incomplete digestive tract • Coelenteron

5. Taxonomic Characteristics • Decentralized nervous system

6. Taxonomic Characteristics • Cnidocytes

7. Everted nematocyst Hydrozoan stinging and capturing prey

8. Cnidarian Dimorphism

9. Cnidarian Dimorphic Life Cycle Colonial hydrozoan

10. Cnidarian Taxonomy • Phylum Cnidaria • Class Hydrozoa • Class Scyphozoa • Class Cubozoa • Class Anthozoa

11. Class Hydrozoa • Most varied of the cnidarian groups • Includes freshwater species (Hydra spp) • Colonial species common (Obelia sp) • Most have typical dimorphic life cycle • Polyp forms dominant (Hydra)

12. A typical Hydrozoan • Hydra • Lacks medusa stage • Asexual - budding • Sexual – gametes • Planula larva

13. hydranths Colonial Hydrozoan - Obelia • Colony of specialized hydranths • Gonangia (gonozooids) – reproduction • Gastrozooids – feeding • Dactyolozooids – catching prey

14. Obelia –schematic diagram • Portuguese Man-O-War (Physaliaphysalis) • Polyp – air bag • Feeding & reproductive hydranths - tentacles

15. Colonial Hydrozoans • Fire Corals • NOT TRUE CORAL • Hydrozoan colony • TRUE CORAL • Anthozoan colony • Cnidocytes cause severe pain

16. Dimorphic Life Cycle and Reproductive Modes • Asexual • Budding • Medusa buds • Polyp buds • Sexual • Gonadal tissue • Gametes • Fertilization, embryogenesis • Planula larvae

17. Class Scyphozoa • Typically thought of as jellyfish • Most have typical dimorphic life cycle • Polyp stage is atypical • Majority of life cycle spent in medusa form

18. Scyphozoan Life Cycle

19. Jellyfishes

20. Lion’s Mane Jelly (Cyaneacapillata)

21. Class Cubozoa

22. Class Cubozoa • Chironex fleckeri • Size of human head with tentacles (4) up to 9 ft long • 18-24 ft of tentacles can deliver enough poison to kill in <5 min.

23. Class Anthozoa • Anemones & Corals • Lack medusa form; largely polyp • Form colonies (especially coral)

24. Class Anthozoa – Typical Polyp Form

25. Class Anthozoa • giant anemone or purple-tipped anemone (Condylactis gigantea) Often harbors cleaning shrimp among its tentacles

26. Anemone Coral & Anemone Fish

28. Class Anthozoa – Hard Coral • Hexacorallia – 6-fold symmetry • Precipitate Ca3(CO3)2 from sea water • become skeletal structures that become coral reefs • Contain zooxanthelae

29. Class Anthozoa – soft corals • Octocorallia – 8-fold symmetry • Form complex tube-like skeletal structures • Lack zooxanthella

30. Class Anthozoa – Soft Corals

31. Reefs • Shallow tropical waters • Hermatypic corals (Class Anthozoa, Subclass hexacorallia, Order Scleractinia) • Contain symbiotic dinoflagellates • Precipitate CaCO3 to form “exoskeleton”

32. Phylum Ctenophora • Comb-jellies • Rows of cells with fused cilia – comb-plates • <100 species • Lack cnidocytes • Complete digestive tract

33. Ctenophore Morphology

34. Ctenophore Morphology

35. Ctenophore Body Forms • Biradial symmetry • Two tentacle clusters • Even # comb rows • Some are bilateral

37. Bioluminescence