1. Cnidarian Diversity

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. Class Anthozoa Subclass Hexacorallia Subclass Alyconaria Order
Sea fans
Sea whips
Sea pens
Organ pipe coral
Precious gold coral
Order
Zoanthidae
Order
Actinaria
Order
Scleractinia
Order
Antipatharia
Zoanthids
Sea anemones
Stony corals
Precious black coral
Wire coral

4. General Characteristics of Cnidaria
Stinging cells
Two stages in life cycle (polyp & medusa)
Blind sack gut
Radial symmetry
Diploblastic
Hydrostatic skeleton
Nerve net
Many colonial, some solitary forms

5. 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.

6. The Cnidarian Life Cycle
The Hydrozoan Life Cycle

7. Hydrozoan Colony

8. Hydrozoan Colonies “Stinging Limu”

9. Hydrozoan Medusa

10. Hydrozoan Medusa

11. Hydrocorals

12. Fire Coral

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

14. Man-of-War Phylum Cnidaria
Coloniality
Man-of-War Phylum Cnidaria

15. Portuguese Man-Of-War
Close Up of a
Portuguese Man-Of-War

16. Class Scyphozoa (Gr. skyphos, cup)
life cycle with both polyps and medusae, but medusae dominate with polyp stage reduced or absent.
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.

17. Scyphozoan Life Cycle scyphistoma strobila strobila scyphistoma ephyra
planula
adult medusa
gametes

18. Sea Jellies

19. Moon Jelly Anatomy

20. Class Cubozoa
(Gr. kybos, a cube)
polyps and medusae stages, but medusae dominate with polyp stage reduced.
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.

21. Seawasp
Box Jellies

22. Box Jelly Anatomy

23. Class Anthozoa lack medusa stage entirely (polyp forms only)
(Gr. anthos, flower)
lack medusa stage entirely (polyp forms only)
mouth with a tubular pharynx that projects inward into the gut
large gut cavity divided by mesenteries that radiate inwards from the body wall
gonads endodermal, borne on the mesenteries
hexamerous (6-part) or octamerous (8-part) radial symmetry or biradial (modified radial symmetry that limits the number of planes that can divide the body into equal halves
includes sea anemones, “true” stony corals, sea fans, sea pens, organ pipe coral, precious black coral, & zoanthids

24. Subclass Zoantharia
Order Actinaria
Sea Anemones

25. Sea Anemone Anatomy

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

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

28. 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

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

30. Subclass Alyconaria Octocorals
8 branched tentacles surrounding the mouth
Both hard and soft forms exist
Ahermatypic- non reef building, no photosynthesis
Five Orders found in Hawaii:
Stolonifera
Pennatulacea (sea pens)
Alcyonacea (soft corals)
Telestacae (snowflake corals)
Gorgonacea (sea fans)

31. Octocorals
Sea pen

32. Organ pipe coral