1. Phylum Coelenterata (Cnidaria & Ctenophora)
Fig. 13.CO

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. Hydrozoan stinging and capturing prey
Everted nematocyst
Hydrozoan stinging and capturing prey
Fig. 13.8

8. Cnidarian Dimorphism
Fig. 13.2

9. Cnidarian Dimorphic Life Cycle
Fig. 13.9
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. Colonial Hydrozoan - Obelia
Colony of specialized hydranths
Gonangia (gonozooids) – reproduction
Gastrozooids – feeding
Dactyolozooids – catching prey
hydranths
Fig. 13.1

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

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

16. Dimorphic Life Cycle and Reproductive Modes
Asexual
Budding
Medusa buds
Polyp buds
Sexual
Gonadal tissue
Gametes
Fertilization, embryogenesis
Planula larvae
Fig. 13.Fig. 13

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
Fig

19. Jelly fishes
Fig

20. Lion’s Mane Jelly (Cyanea capillata)

21. Class Cubozoa
Fig

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
Fig

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

26. Anemone Coral & Anemone Fish
Fig

27. Fig

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
Fig

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

30. Class Anthozoa – Soft Corals
Fig

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

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

33. Ctenophore Morphology
Fig d

34. Ctenophore Morphology
Fig b

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

37. Bioluminescence