nematocyst

     

A cniocyte, cnidoblast or nematocyte, is a type of venomous cell unique to the phylum Cnidaria (corals, sea anemones, hydrae, jellyfish, etc.). It evolved in these aquatic animals as a means for them to catch prey and defend themselves from predators, despite being morphologically simple, lacking a skeleton and usually being sessile; they prey on fish and crustaceans. A cnidocyte fires a structure that contains the toxin, from a characteristic sub-cellular organelle called a cnidocyst (or cnida or nematocyst). This is, for instance, responsible for the stings delivered by jellyfish.

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