Cnidoblasts Cnidoblasts are special cells unique to Cnidarians (jellyfish, corals, sea anemones) that secrete a stinging substance and whose mission is both defense against predators and attack to capture prey. Cnidoblasts are especially abundant in the tentacles and around the mouth.
Cnidoblasts are rounded cells with the nucleus in basal position and a large characteristic organelle, the cnidocyst or nematocyst, over 100 μm, in apical position; Next to it there is a highly modified scourge, the cnidocilium that captures the stimuli that trigger the discharge. The cnidocyst consists of a double-walled invaginated capsule, an operculum that closes it, and a filament wound inside it that is often bristling with spines.
When the cnidocyst is stimulated, evagination of the filament that pierces the skin of the victim or predator occurs and injects the poisonous liquid contained in the capsule. Poison is a mixture of substances with hemolytic and myolytic action; in some cases it is dangerous for man, as in the Australian jellyfish Chironex flecker