1. The Characteristics of Phylum Cnidaria

2. Portuguese Man-Of-War
Phylum Cnidaria
Class
Anthozoa
Class
Hydrozoa
Class
Scyphozoa
Class
Cubozoa
Corals
Anemones
Hydra
Portuguese Man-Of-War
Stinging Limu
Fire Coral
True jellyfish
Box jellies
Sea wasps

3. Characteristics of Phylum Cnidaria
radial symmetry
blind sac gut (= coelenteron or gastrovascular cavity)
diploblastic with mesoglea
polyp and medusa body forms
nematocysts (= specialized stinging capsules)
nerve net
lack excretory, circulatory & respiratory systems
complex life cycle
many colonial forms exhibiting polymorphism

4. oral
Radial Symmetry
Polyp
aboral

5. Jellyfish Phylum Cnidaria
Radial Symmetry
Jellyfish Phylum Cnidaria
Medusa

6. Blind Sac Gut

7. Diploblastic- two germ layers
Phylum Cnidaria

8. Nematocysts

9. Nematocyst Picture
Nematocyst

10. More Nematocysts

11. Nerve Net

12. Diffusion Across the Body Wall

13. Sea Anemones

14. Circulation in a Moon Jellyfish

15. The Cnidarian Life Cycle

16. Coloniality
Coral Phylum Cnidaria

17. Class Hydrozoa (Gr. hydra, water serpent)
polyps and medusa stage, although polyp stage is dominant.
gut cavity of polyp is simple, lacking a pharynx and not divided by mesenteries.
tetramerous (four-part) radial symmetry.
gonads are ectodermal (found in the epidermis).
medusa stage may possess specialized balance organs called statocysts and photosensitive organs called ocelli.
solitary or colonials; some colonial forms highly polymorphic.
includes hydroids (“stinging limu”), fire coral, pink coral, and siphonophores.

18. The Cnidarian Life Cycle
The Hydrozoan Life Cycle

19. Hydrozoan Colony

20. Hydrozoan Colonies “Stinging Limu”

21. Hydrozoan Medusa

22. Hydrozoan Medusa

23. Hydrocorals

24. Fire Coral

25. By-the-Wind-Sailor A Floating Colony of Polyps

26. Coloniality and Polymorphism

27. Poly,orphism in the Portuguese Man- of-War

28. Class Scyphozoa (Gr. skyphos, cup) medusae stage dominate.
polyp stage (scyphistoma) goes through strobilization to produce young medusa.
bell margin lacks a velum.
tetramerous (= four-part) radial symmetry.
gut divided into a complex system of radial canals.
some with a simple single mouth, but many with thousands of microscopic “mouths” at the ends of oral arms.
gonads endodermal (found in the gastrodermis).
specialized sense organs called rhopalia with ocelli & statocysts .
includes some 200 marine species.
"true" sea jellies.

29. Moon Jelly Anatomy

30. Scyphozoan Life Cycle
strobila
scyphistoma

31. Sea Jellies

32. Class Cubozoa medusae dominate stage.
(Gr. kybos, a cube)
medusae dominate stage.
polyp stage develops directly into medusa.
bell margin with a velarium.
tetramerous (= four-part) radial symmetry; bell cube-shaped with tentacles arising from each corner.
gonads endodermal (found in the gastrodermis).
specialized sense organs called rhopalia with ocelli & statocysts .
includes some 15 marine species.
includes box jellies and sea wasps.

33. Seawasp
Box Jellies

34. Box Jelly Anatomy

35. Class Anthozoa Polyp stage only Blind sac gut
(Gr. anthos, flower)
Polyp stage only
Blind sac gut
mesenteries radiate inwards from the body wall
gonads endodermal, borne on the mesenteries
hexamerous (6-part) or octamerous (8-part) radial symmetry or biradial
sea anemones, “true” stony corals, sea fans, sea pens, organ pipe coral, precious black coral, & zoanthids

36. Subclass Zoantharia
Order Actinaria
Sea Anemones

37. Sea Anemone Anatomy

38. Subclass Hexacorallia Order Zoanthidae
No hard skeleton
May be tough and leathery
Shallow water forms
Encrusting forms
Some with zooxanthellae
Polyp stage only

39. Black Coral & Wire Coral
Subclass Hexacorallia
Order Antipatheria
Black Coral & Wire Coral
Black coral
Wire coral

40. Subclass Hexacorallia
Order Scleractinia
“True” Stony Corals
Hermatypic- reef building, zooxanthellae
Common species:
Acroporidae- table
Acroporidea- rice
Agariciidae- flat lobe, corrugated
Faviidae- crust, ocellated
Fungiidae- humpback, mushroom
Pocilloporidae- lace, antler, cauliflower
Poritidae- finger, lobe, plate

41. “True” Stony Corals
lobe
finger
mushroom
Porites rus

42. Octocorals
Sea pen

43. Organ pipe coral