A nematocyst is a small capsule with a thread-like tube coiled inside. When a trigger bristle is disturbed, the coiled tube shoots out and imbeds in whatever triggered it. There is a minute amount of poison injected. The nematocysts are used both for defense and capturing food. Carnivorous, feeding on fish or almost any live animals of suitable size.
Some species live on minute forms caught by ciliary currents.
The sexes are separate. The eggs or sperm are ejected through the mouth. The fertilized egg develops into a planula, which finally settles down somewhere and grows into a single anemone. Asexually they reproduce by pulling apart into 2 halves, or, in some species, small pieces of the pedal disc break off and regenerate into a small anemone. Anemones form some interesting mutualistic relationships with other organisms.