1. Phylum Cnidaria
Hydra, jellyfish, coral, & sea
anemones

2. Phylum Cnidaria
Examples?
• Sea anemones
• Corals
• Sea Pen
• Sea Fan
• Sea Plume
• Hydra
• Jelly fish
• Portuguese Man o’ War
• Box Jelly Fish

3. I. Body Structure
A. Polymorphism =
more than one body form
1. Polyp
2. Medusa

4. 1. Polyp
• Tube with tentacles
around the mouth
• Sessile
Coral polyp

5. Polyp (sea anemone)

6. Polyp (Hydra)

7. 2. Medusa
• Umbrella shape
• Tentacles around mouth
• Motile, Free-swimming

8. • Have D. Tentacles
nematocysts
(stinging
cells)
• Coiled thread
discharges
like a
harpoon
• Contains
neurotoxin
• Paralyzes Discharged
prey nematocyst

9. Discharged nematocyst

10. II. Level of Organization
A. Tissue
B. No organs

11. III. Symmetry
Radial
Compass jellyfish

12. IV. Habitat
A. Aquatic
1. Most Marine
2. Few fresh-water

13. V. Feeding
A. Carnivores Lion’s mane eats
(predators) another jelly
B. Process of feeding
1. Tentacles sting prey with
nematocysts
2. Tentacles grab prey
3. Prey pulled into mouth

14. Process of feeding
4. Prey stuffed into gastro-vascular
cavity (GVC)*
5. GVC makes enzymes, extra-
cellular digestion
6. Undigested food back out mouth
*incomplete digestive tract (no anus)

15. Lion’s mane jellyfish eating

16. VI. Respiration
• Via diffusion

17. VII. Internal Transport
Via diffusion

18. VIII. Excretion
• Via diffusion

19. IX. Response
A. No cephalization or nervous system
B. Nerve net around mouth

20. IX. Response
C. Sensory cells
1. Chemoreceptors (chemicals)
2. Thigmoreceptors (touch)
3. Photoreceptors (light)
Ocelli (eyespots)
4. Statocysts (balance)

21. X. Locomotion
A. Medusa motile, free-swimming
B. Polyps sessile
Exceptions:
1. Hydra tumbles on tentacles
2. Sea anemones glide on pedal disc

22. XI. Reproduction
1. Asexual
budding from polyps or medusae
2. Sexual
a. Medusae release sperm & eggs
b. Larvae free-swimming

23. XII. Ecological Role
A. Predators and prey
B. Neurotoxins in medical research
C. Coral – jewelry, building, reefs (surfing!)
D. Coral reefs - habitat for many
-great biodiversity
- protect coastline
E. Symbiosis with other organisms

24. Class Anthozoa: Sea Anemones

25. Sea Anemones (with sea urchins)

26. Sea Anemones Clown fish with sea
anemone

27. Clown fish & eggs with sea
anemone

28. Clown fish with sea anemone

29. Giant Sea Anemone

30. Rosy Sea Anemone

31. Class Anthozoa: Corals

32. Brain Coral

33. Coral

34. Colt Coral

35. Elkhorn Coral

36. Cabbage Coral

37. Flower Coral

38. Feather Coral

39. Gorgonian Fan Coral

40. Lamellina Coral

41. Sun Coral

42. Subergorgia Coral

43. Soft Coral

44. Sea Pen

45. Sea Fan

46. Sea Plume

47. Class Hydrozoa: Green Hydra

48. Hydra

49. Brown Hydra with buds

50. Brown Hydra eating

51. Hydra eating Daphnia
• Hydra eats Daphnia

52. Class Scyphozoa: True Jellyfish
Fried egg jelly

53. Jellyfish

54. Jellyfish
Red-eyed medusa

55. Jellyfish

56. Jellyfish

57. Jellyfish
Lion’s mane

58. Jellyfish
Purple lion’s mane

59. Upside down Jelly fish

60. Upside down Jelly fish

61. Sea Nettle

62. Jelly and diver

63. Giant Jelly off Coast of Japan

64. Beached Jelly fish

66. Portuguese
Man 0’ War
(a
Hydrozoan), N
OT a true jelly
fish

67. Portuguese Man 0’ War
Tentacles of Physalia physalis

68. Portuguese Man o’ War
vs. Box Jelly fish

69. Class Cubozoa: Box Jellyfish

70. the Box jelly fish