name special cell serving as organs of defence and offence in cnidaria ..

Some interstitial cells of epidermis in Cnidaria become specialized to form stinging cells called cnidoblasts. A cnidoblast is oval in shape with a basal nucleus and contains the sac-like organoid called the nematocyst. Nematocyst is in the form of a capsule enclosing a coiled tube or thread. These nematocysts form organs of defence and offence and are characteristic of Cnidaria.