Actiniae

Actiniae, sea anemones, sessile animals from the phylum Coelenterata and subclass of coral polyps; Actiniae represent skeletonless solitary polyps with fleshy bodies in the form of a bag, the opening of which is surrounded by numerous tentacles. In the coverings of the tentacles and body of the actiniae is embedded a mass of stinging cells, in the protoplasm of which lies a capsule with a coiled spiral thread. Upon contact with another animal, the threads and capsules of the stinging cells are ejected outward and pierce the body of the touching creature. The stinging cells of actiniae are poisonous organs, serving to paralyze prey and to protect the actinium itself. With frequent contact with actiniae, fishermen develop dermatitis with necrosis of the skin coverings on their hands.