The phylum Cnidaria include sea anemones,
sea jellies and corals.
The Greek word "cnidos" means "stinging nettle."
When agitated they eject a barbed thread often with a venom.
The sea anemones in our local tide pools are harmless.
- Radial Symmetry
- Cnidocytes (stinging cells)
- Almost all marine
- Presence of tissues - allows for more complex functions
- One single opening - mouth and anus opening into a blind
pouch (gastrovascular cavity)
- Two body forms Medusa (planktonic) and Polyp (sessile)
- Life cycles may alternate between the two body forms