Common types of cnidarians:

 

Hard corals (sessile colonies)	Feather hydroids (sessile colonies)	Anemones (sessile individuals)	"Jellyfish" (free floating individuals/colonies)

 

 

 

 

Venom apparatus of cnidarians: Nematocyst in the various phases of discharge

(see "General information on cnidarians" for more informations.):

 

a Resting phase.
b When the cnidocil is activated the lid opens.
c The barbed ring is ejected first.
d Final stage with everted venomous thread.