1. Created for use with BIO 2215 Oklahoma City Community College
Phylum Cnidaria
Moore High School
Zoology
Adapted by: Tamara Lookabaugh
Created for use with BIO 2215
Oklahoma City Community College
Dennis Anderson

2. Background Information
9000 Species
700 Million Years Old
Symbiosis with Algae, Coral use them to gain nutrition and build reefs
Cnidocytes containing Nematocysts to capture prey
4 Classes – Hydrozoa, Scyphozoa, Anthozoa, Cubozoa

3. Phylum Cnidaria Marine, Few Freshwater
Radial symmetry with oral and aboral ends
Two body forms
Polyp vs. Medusa
One opening into and out of gastrovascular cavity.
Cnidocytes on tentacles, epidermis and internal
Ocelli and Statocysts
Sexual and Asexual
Nerve net
Diffusion to breathe and release waste
Carnivores, filter feeders

4. Radial symmetry
Hydra Polyp looking over the top

5. Mouth and Tentacles

6. Fig. 13.2
Two Basic body Forms
Fig. 13.2

7. Body Forms Polyp form Medusa form Body is tube with tentacles
Aboral end attached by pedal disc
Anthozoans only have this form
Medusa form
Bell or umbrella shaped
Tetramerous-arranged in fours
Some species have both body forms, medusa is considered the adult, polyp is juvenile
Scyphozoans are mostly medusa form

8. Cnidocyte Structure and Nematocyst Discharge
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Cnidocyte Structure and Nematocyst Discharge

9. Stinging Structure
Cnidocytes produce and hold the stinging structure called NEMATOCYSTS. Cnidocil – hair-like trigger Operculum – door or flap to hold in harpoon Nematocysts – coiled up harpoon like structure (some have toxin and are barbs) Discharge is caused by: High Osmotic pressure, brushing against Cnidocil by prey 40,000x acceleration of gravity, 5 g’s

10. Generalized Cnidarian Life Cycle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Generalized Cnidarian Life Cycle

11. Nervous System
Nerve cells, arranged in a nerve net.

12. Cladogram of Cnidaria Anthozoa Scyphozoa Cubozoa Medusa cuboidal
Loss of medusa
Hydrozoa
Polyp stage reduced
Septa divide gastrovascular cavity
Radial symmetry, cnidocytes, planula larva

13. Class Hydrozoa Means “Water Serpent or Animal”
Cnidocytes present only on epidermis.
Most have Polyp and Medusa stage.
Most are marine and colonial.
Asexual reproduction by budding.
Sexual reproduction via gametes produced by epidermis & released into water.
Monoecious

14. Class Hydrozoa Example Organisms: Hydra (movement) - Freshwater
Pedal laceration, can tumble, climb, walk
Obelia form and life cycle
Gonionemus (different views)
Physalia (video national geographic)
(Portuguese Man O War – open ocean)

15. Budding Asexual cycle Sexual cycle Class Hydrozoa Hydra
Encapsulated
embryo
Ovaries
Budding
Spermaries
Sexual cycle
Asexual cycle
Sperm and Egg unite from sperm
and egg factories

16. Obelia
Hydranth with Gastrozooid “Feeding Polyp”

17. Obelia
Medusae
Medusa bud
Gonangium

18. Obelia
Fig. 13.9

19. Class Hydrozoa Gonionemus
Fig b

20. Class Hydrozoa Gonionemus
Velum

21. Class Hydrozoa Physalia “Portuguese man-o-war”

22. Class Scyphozoa Means “Cup Animal” Largest Jellyfish
Tentacles can reach 70 meters – Open Ocean
Umbrellas have indentations with rhopalium & lappet containing sense organs – ocelli & statocysts
Manubrium(mouth) surrounded by 4 oral arms

23. Class Scyphozoa Aurelia- “Moon Jelly”

24. Strobilation Aurelia Life History
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Aurelia Life History
Strobilation

25. Scyphozoa
are
Dioecious
Fig
Fig

26. Planula Larva Ciliated larva than can swim to a new location
Larva of Scyphozoa are
Created by sperm from one
Male ephyrae that releases
Sperm on female ephyrae
Medusa arm and meets an
Egg to form a zygote which
Become a planula.

27. Aurelia
Oral arm
Gastric pouch
Mouth
Tentacles

28. Class Anthozoa Means “flower animal” Medusa stage absent
Solitary or colonial
Some produce protective skeletons
Tentacles around mouth working with siphinoglyph creating water currents
Cnidocytes internal ejected out
Anemones glide, pedal laceration
All Marine
Protandrous, mono and dioecious

29. Class Anthozoa Sea Anemone

30. Class Anthozoa Metridium
Tentacles
Mouth
Pharynx
Septum
Gastrovascular cavity

31. Symbiosis

32. Class Anthozoa Corals Protective skeleton of calcium carbonate
Polyp retracts when not feeding
Hexacorallia
Found in warm tropical seas

33. Class Anthozoa - Zooxanthellae
Photosynthetic dinoflagellates (brown)
Live in corals
Provide nutrients for coral by photosynthesis
Mutualism

34. Class Anthozoa - Corals Colony of interconnected polyps
Important recyclers of phosphorus and
waste materials
Greatest diversity of all the marine life in
the oceans

35. Class Anthozoa Meandrina Brain Coral (coral spawning link)

36. Class Anthozoa Gorgonia Sea Fan

37. Class Anthozoa Tubipora Pipe Organ Coral

38. Class Anthozoa Actinodiscus Mushroom Coral

39. Class Anthozoa Acropora Staghorn Coral

40. Coral Reefs
Formed over thousands of years from successive layers of coral skeleton deposits (calcium carbonate forms underwater mountains of coral animal skeletons)
The underwater equivalent of the amazon jungle- very high species diversity and biomass
Reefs contain sponges, colonial hydrozoans, anemones, many varieties of coral, fish, many types of worms we’ve not discussed, not to mention bryozoans, ctenophores, protists, bacteria, etc etc..

41. Copyright © The McGraw-Hill Companies, Inc
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Coral Reef Ecosystem
Photo © McGraw-Hill Higher Education, Barry Barker, Photographer

42. Types of Reefs Fringing Reef – Near land with no lagoon
Barrier Reef – Parallel to land with wide and deep lagoon
Atoll – Encircles a lagoon with a steep bank
Bank Reef – Greater distance from land
Largest Reef in the world is the Great Barrier Reef 1200 miles around the coast of Australia.

43. Fringing Reef

44. Barrier Reef

45. Atoll

46. Bank Reef

47. Class Cubozoa- all are dangerous
Means “cube animal” Box jellies
Tentacles arise at four corners from blade-like pendalium.
All marine
Strong swimmers which prey primarily on fish voracious eaters
Stings of some may be fatal within minutes to humans.

48. Class Cubozoa
Gonad
Pedalium
Tentacle

49. Class Cubozoa Chironex fleckeri Sea Wasp
Also known as “THE HAND OF DEATH”

50. Chironex and Irukandji
Video on Chironex
fleckeri
Video on Irukandji
stings

51. The End