1. All contain nematocysts-stinging structures
Phylum Cnidaria
All contain nematocysts-stinging structures

2. Cnidarians Jellies, Anemones, Corals
Dimorphism: Two body shapes during life cycle. (Polyp & Medusa)
Gastrovascular cavity (digestive)
Carnivores
Primitive nerve net
Two distinct tissue layers: Epidermis & Gastrodermis
Cnidocyte (Stinging cells) in tentacles
Radial Symmetry

3. The Polyp and Medusa Stages
Epidermis
Mesoglea
Gastroderm
Tentacles
Mouth/anus
Gastrovascular cavity
Mesoglea
Gastrovascular cavity
Mouth/anus
Tentacles
Polyp
Medusa

4. Feeding Paralyze prey and pulls into mouthgastrovascular cavity
Undigested materials passed out through mouth/anus

5. Respiration, Circulation, Excretion
Diffusion through body walls
Nerve net-network of nerve cells to detect stimuli
Statocysts to determine gravity direction
Ocelli as eyespots to detect light
Response

6. Movement Hydrostatic skeleton-muscles w/ water enable movement
Body contracts to force water out, moving jellyfish in opposite direction.

7. Reproduction and Life cycle
Most cnidarians reproduce both sexually and asexually.
External fertilization

8. Jellyfish Life Cycle Female medusa (2N)
MEIOSIS
Fertilization occurs in the open water, producing many diploid zygotes.
Egg (N)
Adult medusas reproduce sexually by releasing gametes into the water.
FERTILIZATION
Sperm (N)
Each zygote grows into a ciliated larva. The larva eventually attaches to a hard surface and develops into a polyp.
Zygote (2N)
Male medusa (2N)
Young medusa
Swimming larva
Polyp
The polyp buds to release young medusas.
Haploid
Diploid
Budding polyp

9. Classes of Cnidaria Hydrozoa (Serpent Animals) Scyphozoa (Cup Animals)
Anthozoa (Flower Animals)

10. Class Hydrozoa Both body forms: polyp and medusa
Reproduce sexually as medusas.
Example: Portuguese Man Of War

11. Class Scyphozoa True jellies
Medusa form during most of its life cycle.
Lions Mane is the most common in L.I.S.
Butter fish lives in its tentacles.

12. Moon Jelly Free swimming Up to 30 cm wide Found in intertidal zone
Found in L.I.S. (Also in the tanks of Maritime Aquarium)

13. Sea Wasp (another scyphozoan ex.)
Known as box jellyfish
Most powerful venom in the world
Lives in Australia
Can be up to 60 meters in length

14. Class Anthozoa
They are individual or colonies of polyps found in coastal waters.
No medusa stage.
Examples: Sea anemones,Hard corals, sea fans

15. Northern Red Anemone 7.5 cm high, 12.5 cm wide
Attach to rocks under rockweed.
Found in subtidal zones

16. Striped Anemone 2 cm high .5 cm wide
Found on lower rocks on sheltered shores.
Can tolerate reduced salinity.

17. Sea fans

18. Hard corals

19. Phylum Ctenophora Ctenophores Common name: Comb jellies
Contain eight rows of comb plates made of cilia used for locomotion (ciliary combs)
Bioluminescent
No stinging cells
They feed on plankton

20. Comb Jellies